Musnad Ahmed: Hadith 2459

O Abul-Qasim, tell us about some matters we are going to ask you about, which no one will know except a Prophet. Among the things that they asked him was: What food did Isra'eel forbid to himself before the Torah was revealed? He said: “I adjure you by Allah, Who revealed the Torah to Moosa, do you know that Isra'eel Ya'qoob (عليه السلام) became very sick and his sickness lasted for a long time, then he vowed that if Allah healed him from his sickness, he would forbid to himself the drink that he liked best and the food that he liked best. The food that he liked best was camel meat and the drink that he liked best was camel's milk.” They said: Yes, by Allah.