Musnad Ahmad 27:1522

Sulayman ibn Dawud narrated to us, Shu'bah narrated to us, from Sa'id ibn 'Amr, who said: I reached Ibn 'Umar while he had narrated a hadith. I said: "What did he narrate?" They said: He said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: "Ghifar, may Allah forgive them, and Aslam, may Allah grant them peace."