Musannaf Ibn Abi Shayba 3:6259

Hushaym narrated to us, he said: Yunus, Mansur, and 'Awf informed us, from al-Hasan, that they said: "O Messenger of Allah, we have already learned the greeting (salam) upon you, so how is the prayer (salat)?" He said: "Say: 'O Allah, place Your prayers and Your blessings upon Muhammad, just as You placed them upon the family of Ibrahim. Indeed, You are Praiseworthy, Glorious.'"