Abu Dawud Book 21, Hadith Number 3791.
Chapter : Not known.
Narated By Abdullah ibn Abbas : The people of pre-Islamic times used to eat some things and leave others alone, considering them unclean. Then Allah sent His Prophet (PBUH) and sent down His Book, marking some things lawful and others unlawful; so what He made lawful is lawful, what he made unlawful is unlawful, and what he said nothing about is allowable. And he recited: “Say: I find not in the message received by me by inspiration any (meat) forbidden to be eaten by one who wishes to eat it….” up to the end of the verse.