Hadith 508540
Chapter 20: Hajj - كتاب الحج
وَحَدَّثَنِي مَالِكٌ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، كَانَ يَقُولُ فِي الضَّحَايَا وَالْبُدْنِ الثَّنِيُّ فَمَا فَوْقَهُ .
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."
Reference Muwatta Malik 508540
USC-MSA web (English) reference : Book 20, Hadith 151