(12) باب الْمُؤْمِنُ يَأْكُلُ فِي مِعًى وَاحِدٍ
Narrated Abu Huraira:
A man used to eat much, but when he embraced Islam, he started eating less. That was mentioned to the Prophet (ﷺ) who then said, "A believer eats in one intestine (is satisfied with a little food) and a Kafir eats in seven intestines (eats much). "
Reference: Sahih al-Bukhari 5397
In-book reference: Book 70, Hadith 25
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 7, Book 65, Hadith 309