(12) باب الْمُؤْمِنُ يَأْكُلُ فِي مِعًى وَاحِدٍ
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).
Reference: Sahih al-Bukhari 5393
In-book reference: Book 70, Hadith 21
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 7, Book 65, Hadith 305