Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said: Huyayy bin Akhtab and Ka'b bin al-Ashraf came to Makkah to Quraysh and made a pact with them to fight the Messenger of Allah (peace and blessings be upon him). Quraysh said to them: You are the people of ancient knowledge and the People of the Book, so tell us about ourselves and about Muhammad. They (the Jews) said: Well, first tell us what you are and what Muhammad is. Quraysh said: We slaughter fat camels, we give milk to drink instead of water, we free captives, we give water to the pilgrims, and we maintain ties of kinship. They asked: And what is Muhammad? Quraysh said: He is a man cut off, without descendants, who has severed our ties of kinship, and he has been followed by the robbers of the pilgrims, Banu Ghifar. Thereupon they (the Jews) said: Rather, you are better than him and more rightly guided. So Allah, the Mighty and Majestic, revealed this verse: "Have you not seen those who were given a portion of the Book? They believe in al-Jibt and al-Taghut" [Surah al-Nisa': 51], to the end of the verse.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11595