Muwatta Malik, Book 20, Hadith 869 (In-Book) ⓘ
Yahya related to me from Malik from Jafar ibn Muhammad from his father that Ali ibn Abi Talib used to say, "The least difficult thing acceptable as a sacrificial animal is a sheep."
وَحَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ جَعْفَرِ بْنِ مُحَمَّدٍ، عَنْ أَبِيهِ، عَنْ عَلِيِّ بْنِ أَبِي طَالِبٍ، كَانَ يَقُولُ {مَا اسْتَيْسَرَ مِنَ الْهَدْىِ} شَاةٌ .
also referenced under: Book 20, Hadith 167 (USC-MSA)