Imam Muslim narrated from Hudhayfa ibn Asad that the Prophet Muhammad said ﷺ - upon him and his House blessings and peace:

After the sperm-and-ovum drop (nut.fa) has been [in the uterus] forty-two days, Allah sends it an angel that gives it form and fashions its hearing, sight, skin, flesh, and skeleton.

The time frame given cited above is in conformity with embryological observation. The embryo reaches the sixth week without showing the semblance of human form but by the seventh week of its life - about three centimeters in size and beginning to move - that semblance becomes visible in the formation of the essential organs including the sensory organs and grown bone tissue. The arms and legs have lengthened. The foot and hand areas are distinguishable and they have digits. The first recordable brain wave activity occurs.

This organogenesis peaks precisely at 42 days.

According to embryology, the crucial event that determines whether the embryo will develop into a male or female occurs in the second half of the sixth week of gestation.

See for example: How Is Sex Determined? www.pbs.org

The Prophet Muhammad ﷺ - upon him and his House blessings and peace - disclosed the exact same timeframe fourteen centuries ago.

Imam Muslim narrates from Hudhayfa that the Prophet ﷺ said:

The sperm-and-ovum drop falls into the uterus [and remains] for forty nights, after which the angel in charge of fashioning it descends upon it and says, "Lord! Male or female?" Then Allah makes it male or female.

Another version from Hudhayfa in al-Bukhari and Muslim states:

The angel is sent to the sperm-and-ovum drop after it has settled in the uterus for FORTY OR FORTY-FIVE NIGHTS and says, "Lord! Is it to be wretched or happy?" Then this is inscribed. Then he says, "Lord! Is it to be male or female?" Then this is inscribed, together with its deeds, its progeny, its term of life, and its sustenance. Then the records are folded up and nothing more is added nor subtracted.

In the eighteenth week, exactly after the 120-day threshold, respiratory circulation occurs.

The Prophet Muhammad ﷺ - upon him and his House blessings and peace - described ensoulment as taking place exactly after the 120th day as narrated from Ibn Masʿud by al-Bukhari and Muslim in their Sahihs:

For every one of you, the components of his creation are gathered together in the mother's womb for a period of forty days. Then he will remain for two more periods of the same length, after which the angel is sent and insufflates the spirit into him.

The Magnificent Qur'an calls the beginning of respiration "ensoulment" in the literal sense of the insufflation of the life-spirit (nafkh al-ruh):

{ Then He fashioned him and breathed into him of His spirit; and appointed for you hearing and sight and hearts. Small thanks give ye!}
Surat al-Sajda (32:9).

This 4-month stage ends the threshold of permissibility for abortion according to Islamic Law. All the Muslim Jurists concur that the fetus becomes a human being after the fourth month of pregnancy (120 days). The majority of the jurists, as a result, prohibit abortion after that stage and permit it until then provided there is a valid reason. Their totality permit it before forty days while ruling it offensive (makruh).

Al-Bukhari and Muslim narrated from Anas that the Prophet said ﷺ - upon him and his House blessings and peace:

Allah Most High has appointed an angel over the uterus who says,
"Lord! It is now a sperm-and-ovum drop (nut.fa).
"Lord! It is now a thing that clings (ʿalaqa).
"Lord! It is now a thing like chewed flesh (mud.gha)."
Then, when he wants to complete its fashioning, he asks, "Male or female? Happy or wretched? What is his share of sustenance? What is his term of life?" All this is inscribed [as it is] in his mother's belly.

(Since it is established from the hadith of Hudhayfa that gendering occurs "after forty or forty-five nights" in conformity with embryological observation, the above hadith shows that the first forty-day period includes all three stages of nut.fa - mud.gha- ʿalaqa. Contrary to what Bucaille misunderstood, these stages do not correspond to three 40-day periods.)

Embryogenesis recognizes the very same stages as in the following description adapted from the University of Maryland online medical encyclopedia www.umm.edu :

[NUTFA - Sperm-and-ovum drop] A single sperm penetrates the mother's egg cell (ovum) and the developing child gets half of its genetic information (in the form of DNA) from the mother (this is contained in the egg), and half from the father (from the sperm). The resulting single cell is called a zygote. The zygote spends the next few days traveling down the Fallopian tube and divides to form many attached cells. A ball of cells is produced, each cell including a copy of the genes that will guide the development of the baby. Once there are about 32 cells, the developing baby is called a morula. With additional cell division, the morula becomes an outer shell of cells with an attached inner group of cells. Now the developing baby is in the "blastocyst" stage. The outer group of cells will become the membranes that nourish and protect the inner group of cells which will become the embryo (the next stage for the future baby).

[ʿALAQA - "A thing that clings"] The blastocyst reaches the uterus at roughly the fifth day, and implants into the uterine wall on about day six. At this point in the mother's menstrual cycle, the endometrium (lining of the uterus) has grown and is ready to support a fetus. The blastocyst adheres tightly to the endometrium where it receives nourishment via the mother's bloodstream. During the time between implantation and the eighth week, the cells of what is now called the embryo not only multiply, but begin to take on specific functions. This process is called differentiation and is necessary to produce the varied cell types that make up a human being (such as blood cells, kidney cells, nerve cells, etc.).

[MUDGHA - "A thing like chewed flesh"] This is the "teeth-mark" or "masticated border" appearance of the human-formed fetus in the apt Qur'anic phrasing for the post-embryonic stage. The end of the eighth week marks the beginning of the "fetal period" and the end of the "embryonic period."

We might say that the terminology nut.fa-'alaqa-mud.gha roughly corresponds to the following sequence:

NUTFA [1] zygote/morula
ʿALAQA [2] blastocyst/embryo
MUDGHA [3] fetus.

It has become common practice in certain countries to have prospective spouses take a test of compatibility in order to curtail the probability of congenital disorder or childlessness that their match might produce. As unromantic or even manipulative as such notions of selective mating and genetic checking might be, they are nevertheless rooted in the fact that marriage is essentially for procreation, and parental heredity plays a definite role in the formation of progeny, at all sorts of levels. The Prophet Muhammad ﷺ - upon him and his House blessings and peace - gave the following advice on this topic:

Al-Nasa'i, Abu Dawud, Ibn Majah, and Ahmad narrated from Maʿqil ibn Yasar t:

A man came to the Prophet ﷺ and said, "I have set my eye on a woman of lineage and beauty except that she cannot [or will not] have children. Shall I marry her?" The Prophet ﷺ said no. The man came back a second time and the Prophet ﷺ forbade him again. When he came back a third time the Prophet said: "Marry the loving, child-bearing woman (al- wadud al-walud) for I will boast of you before the nations."

This advice applied to women also. Ibn Majah, Ibn Abi Shayba, al-Hakim, al-Diya' al-Maqdisi, Ibn ʿAdi and others narrate from the mother of the Believers ʿA'isha and from Anas that the Prophet ﷺ said:

Choose well where your seeds will go.

ʿA'isha's narration continues:

Marry suitable matches (akfa') and give your daughters away to suitable matches.

One version adds:

For women give birth to [boys] the likes of their brothers and [girls] the likes of their sisters.

The latter narration is confirmed by the report - in al-Bukhari, Muslim, the Sunan except Ibn Majah, and Ahmad - from Anas that the Prophet said:

The son of the sister of a people is one of them.

In this way comes the reply to the question: How could one tell the child-bearing prospect from her opposite, and anticipate the kind of boy and girl she is likely to bear? By looking at her brothers and sisters, her uncles and aunts, and so forth. There is more on this in the hadiths of dominant and recessive characters in heredity.

The Prophet Muhammad ﷺ - upon him and his House blessings and peace - revealed that chromosomes bear genes representative not only of each immediate parent and their siblings, but of ninety-nine strains for each parent, reaching back through the maternal and paternal family lines all the way to the first man and woman. The Prophet ﷺ even used language such as "threading" (salaka) - in the same way biogenetics describes DNA today.

Ibn Rajab said in his masterpiece Jamiʿ al-ʿUlum wal- Hikam that al-Tabarani and Ibn Mandah in al-Tawhid - among others - narrated with a good chain of transmission from Malik ibn al-Huwayrith that the Prophet said:

Truly, when Allah wants to create a servant, the man has intercourse with the woman and his water flies into every vein/strain (ʿirq) and nerve (ʿasab) of hers. When the seventh day comes, Allah gathers it up and brings before it every strain between it and Adam: {Into whatsoever form He will, He casts you} (Q 82:8).

Hence the Prophet ﷺ also said - as narrated from the Tabiʿi Ibn Burayda by al-Hakeem al-Tirmidhi in Nawadir al-Usul - to the wife of the Ansari after she gave birth to a black child and pleaded her innocence:

You speak the truth. You have ninety-nine strains and so does he. On the time of conception all those strains shudder and there is none but it asks Allah Most High to determine resemblance through it.

This is confirmed by the Magnificent Qur'an as mentioned by Ibn Rajab in Jamiʿ al-ʿUlum wal-Hikam: Saʿid ibn Mansur in his Sunan, Ibn Abi Hatim in his Tafsir, al-Tabarani, and others narrated that Ibn Masʿud explained the Qur'anic term {nutfatin amshajin} usually translated "mixed fluid drop" to mean "ʿuruquha" or the strains contained in the drop, so that the verse reads:

{We created man from a drop containing strains (nutfatin amshajin) to test him}
(Q 76:2)

The seven-day timing of the hadith of Ibn al-Huwayrith, again, is astonishingly accurate. The sperm-and-ovum single cell or zygote spends days traveling down the Fallopian tube, growing and dividing to develop into a morula then a blastocyst. The blastocyst reaches the uterus at roughly the fifth day and implants into the uterine wall on about day six. Only then in the mother's menstrual cycle has the lining of the uterus or endometrium grown and is ready to support a fetus. The blastocyst then adheres tightly to the endometrium where it receives nourishment via the mother's bloodstream.

- expired link (before 2017) - www.1uphealth.com/health/fetal_development

Another hadith uses DNA "threading" terminology - a feat in itself regardless of the authenticity of its attribution to the Prophet, upon him peace. Al-Tabari, Ibn Abi Hatim, Ibn Marduyah, al-Tabarani, and others narrate:

Rabah ibn Qasir relates the Prophet ﷺ said to him - upon him blessings and peace: "What child did you get?" He replied, "Messenger of Allah, what else? Either a boy or a girl." The Prophet said: "Who does he resemble?" He replied, "Who else? Either his mother or his father!" The Prophet ﷺ said: "None of you should say that. Truly, when the sperm-and-ovum drop settles in the uterus, Allah brings it every lineage between it and Adam. Have you not recited this verse? {Into whatsoever form He will, He casts you (rakkabak)} (82:8). Meaning, 'threads you' (salakak)."

The Magnificent Qur'an refers to the fact that creation does not proceed except from a "mingling" - the combination of both the sperm and the ovum:

{We created man from a drop of mingled fluid (nutfatin amshajin) to test him; so We make him hearing, knowing}
(Sura "Time" also titled "Man" 76:2)

This combination is the new fetus. How is gender finally decided? What are the determining factors that cause the father's X chromosome rather than his Y chromosome - or vice-versa - to finally fuse with the mother's X chromosome, resulting in a girl or a boy?

"The ovaries are homologous with the testes in the male" (Gray's Anatomy). The male seminal fluid is thick and whitish while the ovary secretes and discharges a thin yellowish substance called corpus luteum or "golden- yellow body." 1,400 years ago the Prophet Muhammad ﷺ - upon him and his house blessings and peace - mentioned both.

Further, he revealed that when the father's fluid - gamete, chromosomes and genes - prevails upon the mother's, the child will take after the father; but if the mother's fluid - gamete, chromosomes and genes - prevails, the child will take after the mother.

Imam Muslim narrated in his Sahih from Anas ibn Malik:

Umm Sulaym [Anas' mother] said that she once asked the Prophet about a woman that sees, upon waking up, [traces of an emission of fluid] just as a man can. The Prophet ﷺ replied, "When a woman sees this, let her wash from head to toe." Umm Sulaym said that she felt shy to ask such a thing and added, "Can such a thing truly take place?" The Godsent Prophet said ﷺ - upon him blessings and peace: "Yes, it can. Where else does [parental] resemblance originate [in the child]? Indeed, the fluid of the man is thick and white while the fluid of the woman is thin and yellow. Whichever of the two surpasses (ʿala) or precedes (sabaqa) the other, dictates resemblance."

Another narration has the "prevailing fluid" determine sex rather than resemblance. Muslim narrates from Thawban:

While I was standing beside the Prophet ﷺ, one of the rabbis of the Jews came [...] then said: "I have come to ask you about something no one on earth would know except a Prophet [...]. I have come to ask you about the child." The Prophet said: "The fluid of the man is white and that of the woman yellow. When they unite and the male fluid prevails upon the female fluid, their child is male (adhkaraa) by Divine permission. When the female fluid prevails upon the male fluid, their child is female (aanathaa) by Divine permission." The Jew said: "What you said is true; you are truly a Prophet!" He turned and went away. The Messenger of Allah said: "This man just asked me about things of which I had no knowledge whatever until Allah had that knowledge brought to me!"

The above hadith can be interpreted to mean that the mother's fluid somehow draws the X-carrying sperm into the egg cell and blocks the Y-carrying one. However, it is an observable fact that in the majority of cases a child mostly resembles the parent of the opposite sex. More than this, the hadith of ʿA'isha on marital selection stated that "women give birth to [boys] the likes of their brothers and [girls] the likes of their sisters." It is possible, therefore, to surmise two other explanations:

(i) The "male" and "female" fluids mentioned in the second hadith are not parent-differentiated as in the first but rather both refer to the father's sperm in the sense that the male-chromosome-bearing part of the sperm is thick and white at the microscopic level while the female-chromosome-bearing part of the same sperm is thin and yellow.

(ii) The narrator(s) of the second narration might have made a mistake in the wordings "their child is male" and "their child is female" which should read, instead, "their child takes after the male line" and "their child takes after the female line" respectively. If so, the second hadith is in substance a repetition of the first. Allah knows best.

The latter alternative is the strongest in light of al-Bukhari's variant version of Thawban's hadith from Anas ibn Malik, identifying the rabbi as ʿAbd Allah ibn Salam:

News of the coming of the Prophet to Madina reached ʿAbd Allah ibn Salam. He went to see him and ask him questions: "I want to ask you of three things which none but Prophets know. What is the first of the conditions of the last Hour? What is the first meal the people of Paradise eat? Why does a child resemble his father or mother?" The Prophet ﷺ said: ... The first of the conditions of the last Hour is a fire that will gather them from East to West. The first meal the people of Paradise eat is whales' sweetbreads. As for the child, then if the man's fluid precedes that of the woman, he draws the child to him; if hers, she draws the child to her." He said: "I bear witness that there is no God but Allah and that you are the Messenger of Allah."

Among the four principles of hereditary phenomena discovered and formulated by the founder of modern genetics, the Austrian monk and botanist Gregor Mendel (1822-1884 CE), is the "law of dominance," which states that in every individual there is a pair of determining factors for each unit character, one from each parent; if these factors are different (heterozygous), one character (the "dominant") appears in the organism, the other (the "recessive") being latent. The "dominant character" designates that one of any pair of two-gene hereditary factors which, when both are present in the germ plasm, dominates over the other and appears in the organism. It is opposed to the "recessive character" which designates that one of any pair of hereditary factors which, when both are present in the germ plasm, remains latent and may or may not reappear down the line.

The Prophet Muhammad ﷺ - upon him and his House blessings and peace - differentiated between dominant and recessive character 1,400 years ago, when he revealed that a characteristic or "strain" (ʿirq, lit. "blood- vessel") that lay deeply buried for several generations - "recessive" - may appear again down the line. He also noted the similarity of heredity laws in man with those in animals. Both disclosures are in complete agreement with our present knowledge of the laws of heredity.

In al-Bukhari, Muslim, the four Sunan, and the Musnad, Abu Hurayra narrated:

A desert bedouin came to the Messenger of Allah and said: "My wife has given birth to a black child and I have disowned him!" The Messenger of Allah asked him: "Do you own camels?" The man said yes. "What color are they?" "Red." "Any gray ones among them?" "Indeed, there are gray ones among them!" "And how do you think this [color] came to them?" "Messenger of Allah, some strain must have drawn it out! (ʿirqun nazaʿahu)." "Maybe the same happened here, some strain must have drawn him out." He did not allow him to disown him.

A rare mursal narration from the Tabiʿi Ibn Burayda in Asl 148 of al-Hakeem al-Tirmidhi's Nawadir al-Usul specifies ninety-nine potential hereditary strains per parent:

The wife of a man from the Ansar bore him a black child. He took her by the hand and went to see the Messenger of Allah. She said: "I swear by the One that sent you with the truth! He married me a virgin and I never seated anyone in his place since!" The Prophet ﷺ said: "You speak the truth. You have ninety-nine strains and so does he. On the time of conception all those strains shudder and there is none but it asks Allah Most High to determine resemblance through it."

Thus, a latent character may find its way to the newborn centuries later without resemblance to either of the immediate parents. Hence the Prophet ﷺ prayed for strength and excellence in his sensory organs and those of his Companions and very frequently asked that they pass on to and "dominate" in his offspring and theirs, as narrated by al-Tirmidhi and others from Ibn ʿUmar:

The Prophet seldom rose from a sitting before he first supplicated in these words for his Companions (RA). "O Allah, grant us to enjoy use of our hearings, our sights, and our strengths as long as You give us life, and make that our inheritor [i.e. pass it on to our posterity] ... "

Al-Tirmidhi and others also narrate from ʿA'isha, the wife of the Prophet ﷺ:

The Messenger of Allah used to say, "Allah, my Lord! Grant me good health in my body and grant me good health in my sight and make that the inheritor after me. There is no god except Allah, the Gentle, the Generous! Glory to Allah the Lord of the Magnificent Throne! Praise and thanks to Allah Lord of the worlds!"

The Prophet's use of the word "inheritor" can now be understood in the light of Mendel's discoveries on the dominant genes exerting a controlling influence in heredity and causing the recessive genes not to appear in the offspring.

The Prophet Muhammad ﷺ - upon him and his House blessings and peace - described the state of the healthy newborn as al-fitra - the pristine state - and equated this primordial perfection with the religion of Islam, the natural religion. In the process he alluded to the fact that deformity in the newborn is so rare as to being close to inexistant.

Al-Bukhari, Muslim, the four Sunan, and the Musnad narrated from Abu Hurayra that the Prophet ﷺ said:

There is no child born except in pristine disposition (fitra). Then the two parents turn their child into a Jew, a Christian, a Magian. Likewise, the animal gives birth to a fully formed calf. Do you see in it the least disfigurement?

Muslim and Ahmad narrate from Ibn Masʿud t that when someone asked if the apes and swine of that time were descendants of the apish and swinish disfigurement of the Sabbath-breakers (Q 2:65, 5:60, 7:166) the Prophet ﷺ replied:

Allah Most High never gave offspring nor posterity to the deformed.

These two hadiths anticipate, 1,400 years ago, the observations of modern obstetrics and embryology. We do not see many deformed babies in real life since the majority of grossly malformed embryos and fetuses never come to term. Yet, even if deformed fetuses are born and survive, they cannot reproduce.

Hajj Gibril
GF Haddad
[5-7 Apr 2003]