Source: Tafseer Ibn Katheer from SuratAl Baqara
(2.80. And they (Jews) say, “The Fire shall not touch us but for a few numbered days.” Say (O Muhammad to them): “Have you taken a covenant from Allah, so that Allah will not break His covenant Or is it that you say of Allah what you know not”)
Allah mentioned the claim of the Jews, that the Fire will only touch them for a few days, and then they will be saved from it. Allah refuted this claim by saying,
(Say (O Muhammad to them): “Have you taken a covenant from Allah’). Hence, the Ayah proclaims, `if you had a promise from Allah for that, then Allah will never break His promise. However, such promise never existed. Rather, what you say, about Allah, you have no knowledge of and you thus utter a lie about Him.’ Al-`Awfi said that Ibn `Abbas said about the Ayah,
(And they (Jews) say, “The Fire shall not touch us but for a few numbered days.”). “The Jews said, `The Fire will only touch us for forty days.”’ Others added that this was the period during which the Jews worshipped the calf.
Also, Al-Hafiz Abu Bakr bin Marduwyah reported Abu Hurayrah saying,
(When Khaybar was conquered, a roasted poisoned sheep was presented to the Prophet as a gift (by the Jews). The Messenger of Allah ordered, `Assemble before me all the Jews who were here.’ The Jews were summoned and the Prophet said (to them), `Who is your father’ They replied, `So-and-so.’ He said, `You have lied; your father is so-and-so.’ They said, `You have uttered the truth.’ He said, `Will you now tell me the truth, if I ask you about something’ They replied, `Yes, O Abul-Qasim; and if we should tell a lie, you will know our lie as you have about our fathers.’ On that he asked, `Who are the people of the (Hell) Fire’ They said, `We shall remain in the (Hell) Fire for a short period, and after that you will replace us in it.’ The Prophet said, `May you be cursed and humiliated in it! By Allah, we shall never replace you in it.’ Then he asked, `Will you tell me the truth if I ask you a question’ They said, `Yes, O Abul-Qasim.’ He asked, `Have you poisoned this sheep’ They said, `Yes.’ He asked, `What made you do so’ They said, `We wanted to know if you were a liar, in which case we would get rid of you, and if you were a Prophet then the poison would not harm you.’) Imam Ahmad, Al-Bukhari and An-Nasa’i recorded similarly.