مُوَطَّأُ مَالِكٍ
Muwatta Malik 869
Hajj
وَحَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ جَعْفَرِ بْنِ مُحَمَّدٍ، عَنْ أَبِيهِ، عَنْ عَلِيِّ بْنِ أَبِي طَالِبٍ، كَانَ يَقُولُ {مَا اسْتَيْسَرَ مِنَ الْهَدْىِ} شَاةٌ .
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."
Arabic/English book reference: Book 20, Hadith 167