صحيح البخاري

Narrated Nafi`:

Ibn `Umar never used to take his meal unless a poor man was called to eat with him. One day I brought a poor man to eat with him, the man ate too much, whereupon Ibn `Umar said, "O Nafi`! Don't let this man enter my house, for I heard the Prophet (ﷺ) saying, "A believer eats in one intestine (is satisfied with a little food), and a kafir (unbeliever) eats in seven intestines (eats much food).