Muwatta Malik, Book 49, Hadith 20 (USC-MSA)

Yahya related to me from Malik from Abu'z-Zinad from al-Araj from Abu Hurayra that the Messenger of Allah, may Allah bless him and grant him peace, said, "The food of two is enough for three, and the food of three is enough for four."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ أَبِي الزِّنَادِ، عَنِ الأَعْرَجِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏ "‏ طَعَامُ الاِثْنَيْنِ كَافِي الثَّلاَثَةِ وَطَعَامُ الثَّلاَثَةِ كَافِي الأَرْبَعَةِ ‏" ‏ ‏.‏

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also referenced under: Book 49, Hadith 1693 (In-Book)