Sahih Muslim Book 023, Hadith Number 5115.
Chapter : A believer eats in one intestine whereas a non-believer eats in seven intestines.
Nafi' reported that Ibn 'Umar saw a poor man. He placed food before him and he ate much. He (Ibn 'Umar) said: He should not come to me, for I heard Allah's Messenger (may peace be upon him) as saying that the non-Muslim eats in seven intestines.