{And there is none of the People of the Scripture but he will certainly believe in him before his death, and on the Day of Resurrection he will be a witness against them.} 4:159

ʿAbd al-Razzaq (d. 211) in his Tafsir (1:177-178) cites reports from al-Kalbi, Qatada, and al-Hasan stating that it means "believe in ʿIsa before ʿIsa's death," and a report from Shahr ibn Hawshab that it means "believe in ʿIsa before the death of the Jew or Christian."

Imam Ibn Jarir al-Tabari (d. 310) said in his Tafsir (6:18-21): "Commentators differ on the meaning of this verse, some saying that it means 'believe in ʿIsa before ʿIsa's death'." He then cites reports to that effect from Ibn ʿAbbas, al-Hasan, Qatada, Abu Malik, and others. Then he said: "Others said that it means believe in ʿIsa before the death of the Jew or Christian." He then cites reports to that effect from Ibn ʿAbbas, Ubay, Mujahid (Tafsir 1:180-181), ʿIkrima, al-Dahhak, al-Hasan, Muhammad ibn Sirin, and others. Then he said: "Others said that it means believe in Muhammad - blessings and peace upon him - before the death of the Jew or Christian." He cites a report to that effect from ʿIkrima. Then Imam al-Tabari states that the likeliest view to be correct is: there is none of the People of the Scripture but he will certainly believe in ʿIsa before ʿIsa's death.

Al-Bukhari and Muslim in their Sahihs: Abu Hurayra, may Allah be pleased with him, narrated that Allah's Messenger ﷺ said: "By Him in Whose hand is my soul, the Son of Mary - peace be upon him - will soon descend among you as a just ruler. He shall destroy the crosses, slay the swine, abolish the Jizya, and wealth shall pour forth to such an extent that no one will accept it. A single prostration shall be better than the whoile world and all that is in it." Abu Hurayra added: "Recite, if you will, Allah's saying: {And there is none of the People of the Scripture but he will certainly believe in him before his death, and on the Day of Resurrection he will be a witness against them.}"

In al-Tabari, Ahmad, and Ibn Marduyah's narration of the above report Abu Hurayra adds: "Meaning, ʿIsa's death."

Explanations narrated from Ibn ʿAbbas:

1. "Before his death meaning: before ʿIsa's death." Narrated by Sufyan al-Thawri, Tafsir (p. 98) and al-Tabari in his Tafsir.
2. "Before his death meaning: before the Jew's death." Narrated by al-Tabari and Ibn Abi Hatim in their Tafsirs as stated by al-Suyuti in al-Durr al-Manthur (2:733).
3. "Before his death is read Before their [i.e. the People of Scripture's] death in Ubayy's canonical reading." Narrated by Abu Dawud al-Tayalisi, Saʿid ibn Mansur, al-Tabari and Ibn al-Mundhir in their Tafsirs as stated by al-Suyuti in al-Durr al-Manthur (2:733).
4. "Before his death meaning: at the time ʿIsa comes forth, Allah's blessings upon him." Sahih according to al-Hakim in al-Mustadrak (1990 ed. 2:338).

Ibn al-Jawzi (d. 597) in his Tafsir (2:247-248) states that Ibn ʿAbbas explained "the People of the Book" here to mean the Jews, while al-Hasan and ʿIkrima explained it to mean both the Christians and the Jews. Then he stated that Ibn ʿAbbas and the vast majority considered the pronoun in "believe in him" to refer to ʿIsa, while ʿIkrima said it refers to the Prophet Muhammad ﷺ . Then he stated that there were two positions concerning the pronoun in "before his death":

"One explanation is that the pronoun refers to the person who believes. Ibn ʿAbbas said: There is no Jew except he believes in ʿIsa before he dies, even if he falls from the top of a roof, and Ubay's reading has: before their death." This is also the position of Mujahid and Saʿid ibn Jubayr. Al-Dahhak also narrated from Ibn ʿAbbas: The Jew believes in ʿIsa before his death, and the soul of the Christian does not leave him except he witnesses that ʿIsa is a servant. While ʿIkrima narrated: The soul of the Jew or Christian does not leave him except he bears witness to the prophethood of Muhammad ﷺ .

"Another explanation is that the pronoun refers to ʿIsa. Ibn ʿAbbas said that at the time he descends there shall not remain on the face of the earth any Jew or Christian or anyone that worships other than Allah, all believing in ʿIsa and following him as the spirit from Allah and His Word, His servant and Messenger ﷺ . This is the position of Qatada, Ibn Zayd, and Ibn Qutayba, and Ibn Jarir al-Tabari chose it."

Al-Qurtubi (d. 771) in his Tafsir (6:11) states: "It means believe in ʿIsa before the Jew's or Christian's death, and it is of no benefit to him. It is also said that it means before ʿIsa's death, but the former interpretation is more likely."

Ibn Kathir (d. 774) in his Tafsir (1:367): "The pronoun in the clause 'before his death' refers to ʿIsa, upon him peace, meaning there is none of the People of the Scripture but he will certainly believe in ʿIsa when he descends to the earth before the Day of Resurrection. At that time he shall abolish the jizya and nothing shall be accepted other than Islam."

Abu al-Suʿud (d. 951) in his Tafsir (2:252): "The pronoun 'his' refers to an omitted attributee, while the previous pronoun ['him'] refers to ʿIsa. Meaning: there is not one of the People of the Scripture but will certainly believe, before his soul is taken away, in the fact that ʿIsa ibn Maryam is Allah's servant and Messenger. That is: when belief no longer counts because legal responsibility (taklif) ceases at that time. This is reinforced by one of the canonical readings which states: ʿbut THEY will certainly believe in him before THEIR death.' [Reading of Ubayy as narrated from Ibn 'Abbas in Tafsir Ibn Kathir 1:578.] It is related from Ibn ʿAbbas that he explained it in this way.

"It has also been said that both pronouns refer to ʿIsa, at which time there will be but one community on earth, lions and tigers and wolves shall graze side by side with the camels and cattle and sheep etc. for forty years, after which ʿIsa shall die and be buried.

"It has also been said that the pronoun 'him' [in the clause 'shall believe in him'] refers to Allah. It has also been said that it refers to Muhammadﷺ ."

All of the commentators agree that in either case - whether belief in ʿIsa takes place when ʿIsa rules on earth or before a Jew or Christian's death - it is a belief that does not benefit, since it comes at a time when the responsibility to believe has been lifted. In the first case there will not be other than Islam on the face of the earth while the second case occurs at the time of one's death. As for the clause "he will be a witness against them" it means: in the sense that he conveyed his message faithfully and declared his own servanthood for all to know. Cf. Ibn al-Jawzi (2:250).

And Allah knows best.