Yahya related to me from Malik from Nafi that Abdullah ibn Umar would guard against animals and camels which were young or had physical defects as sacrifices.

Malik said, "That is what I like best of what I have heard ."
Muwatta Malik Book 23, Hadith 2
← Previous Hadith Yahya related to me from Malik from Amr ibn al-Harith from Ubayd ibn Fayruz from al-Bara ibn Azib that the Messenger of Allah, may Allah bless him and grant him peace, was asked what animals should be avoided as sacrifices. He indicated with his hand and said, "Four." Al-Bara pointed with his hand and said, "My hand is shorter than the hand of the Messenger of Allah, may Allah bless him and grant him peace. A lame animal whose lameness is evident, a one-eyed animal which is clearly one-eyed, an animal which is clearly ill, and an emaciated animal with no fat on it."

Muwatta Malik Book 23, Hadith 1 Next Hadith → Yahya related to me from Malik from Nafi that one time Abdullah ibn Umar wanted to sacrifice an animal at Madina. Nafi said, "He told me to buy him an excellent horned ram, then to sacrifice it on the Day of Sacrifice in the place where the people prayed." Nafi continued, "I did so and when the ram was sacrificed, it was carried to Abdullah ibn Umar who shaved his head. He was ill, and did not attend the Id with the people." Nafi added, "Abdullah ibn Umar used to say, 'Shaving the head is not obligatory for someone who sacrifices an animal.' Ibn Umar would do so however."

Muwatta Malik Book 23, Hadith 3