Musnad Ahmad 27:1941

Rawh narrated to us, Ibn Jurayj narrated to us, he said: It reached me, from Nafi’, from Ibn ‘Umar: "That the Prophet, peace and blessings of Allah be upon him, used to slaughter (nahr) on the day of Adha in Medina." He said: "And when he did not slaughter (nahr), he sacrificed (dhabh)."