Musnad Abu Ya'la al-Mawsili 115:295

Ubayd Allah narrated to us, Yahya bin Sa'id narrated to us, Shu'bah narrated to us, from Qatadah, from Anas, who said: The Messenger of Allah (may Allah bless him and grant him peace) sacrificed two white-and-black horned rams. He slaughtered them with his own hand. It is as if I am looking at their sides, with his foot upon them, mentioning the name of Allah and glorifying Allah.