Muwatta Malik, Book 20, Hadith 151 (USC-MSA) ⓘ
Yahya related to me from Malik from Nafi that Abdullah ibn Umar used to say, about sacrificial animals, "Six-year-old camels, three- year-old cows and sheep, or older than these."
وَحَدَّثَنِي مَالِكٌ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، كَانَ يَقُولُ فِي الضَّحَايَا وَالْبُدْنِ الثَّنِيُّ فَمَا فَوْقَهُ .
also referenced under: Book 20, Hadith 854 (In-Book)