سنن أبي داود

Narrated Abdullah ibn Qurt:

The Prophet (ﷺ) said: The greatest day in Allah's sight is the day of sacrifice and next the day of resting which Isa said on the authority of Thawr is the second day. Five or six sacrificial camels were brought to the Messenger of Allah (ﷺ) and they began to draw near to see which he would sacrifice first. When they fell down dead, he said something in a low voice, which I could not catch. So I asked: What did he say? He was told that he had said: Anyone who wants can cut off a piece.