Muwatta Malik, Book 2, Hadith 26 (USC-MSA)

Yahya related to me from Malik from Muhammad ibn al-Munkadir that the Messenger of Allah, may Allah bless him and grant him peace, was invited to eat, and some bread and meat was brought to him. He ate some of it, and then did wudu and prayed. Then more of the same food was brought and he ate some more and then prayed without doing wudu.

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ مُحَمَّدِ بْنِ الْمُنْكَدِرِ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم دُعِيَ لِطَعَامٍ فَقُرِّبَ إِلَيْهِ خُبْزٌ وَلَحْمٌ فَأَكَلَ مِنْهُ ثُمَّ تَوَضَّأَ وَصَلَّى ثُمَّ أُتِيَ بِفَضْلِ ذَلِكَ الطَّعَامِ فَأَكَلَ مِنْهُ ثُمَّ صَلَّى وَلَمْ يَتَوَضَّأْ ‏.‏

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also referenced under: Book 2, Hadith 56 (In-Book)