Sahih Bukhari Volume 004, Book 056, Hadith Number 666.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 56. Virtues and Merits of the Prophets (PBUH) and his Companions
Narated By Ibn Abbas : I heard 'Umar saying, "May Allah Curse so-and-so! Doesn't he know that the Prophet said, 'May Allah curse the Jews for, though they were forbidden (to eat) fat, they liquefied it and sold it."