Imam Malik's Muwatta, Chapter: Shortening the Prayer

Yahya related to me from Malik from Nuaym ibn Abdullah al-Mujmirthat Muhammad ibn Abdullah ibn Zayd told him that Abu Masud al Ansari said, "The Messenger of Allah, may Allah bless him and grant him peace, came to us at the gathering of Sad ibn Ubada. Bashir ibn Sad said to him, 'Allah has ordered us to ask for blessings on you, Messenger of Allah. How should we do it?' The Messenger of Allah, may Allah bless him and grant him peace, remained silent until we wished we had not asked him. Then he told us to say, 'O Allah, bless Muhammad and the family of Muhammad as You blessed Ibrahim, and give baraka to Muhammad and the family of Muhammad as You gave baraka to the family of Ibrahim. In all the worlds You are worthy of Praise and Glorious,' and then give the taslim as you have learnt." Allahumma salli ala Muhammad wa ali Muhammad kama sallaita Ibrahim, wa baraka ala Muhammad wa ali Muhammad kama baraktaala ali Ibrahim. Fi'l alamin, innaka Hamidu'm - Majid.