Sahih Bukhari
Virtues and Merits of the Prophet (pbuh) and his Companions
Volume: 004 / Book Number: 056 / Hadith Number: 666
Narrated 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. "