Muwatta Malik, Book 23, Hadith 1041 (In-Book)

Yahya related to me from Malik that Ibn Shihab said, "The Messenger of Allah, may Allah bless him and grant him peace, only sacrificed one camel or one cow for himself and his family." Malik said, "I do not know which of them Ibn Shihab said."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، أَنَّهُ قَالَ مَا نَحَرَ رَسُولُ اللَّهِ صلى الله عليه وسلم عَنْهُ وَعَنْ أَهْلِ بَيْتِهِ إِلاَّ بَدَنَةً وَاحِدَةً أَوْ بَقَرَةً وَاحِدَةً ‏.‏ قَالَ مَالِكٌ لاَ أَدْرِي أَيَّتَهُمَا قَالَ ابْنُ شِهَابٍ ‏.‏

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also referenced under: Book 23, Hadith 11 (USC-MSA)