From Sahih Bukhari (Hadith 6360):
Narrated Abu Humaid As-Saidi:The people said, "O Allah's Messenger (ﷺ) ! How may we send Salat on you?" He said, "Say: Allahumma Salli 'ala- Muhammadin wa azwajihi wa dhurriyyatihi kama sal-laita 'ala `Ali Ibrahim; wa barik 'ala Muhammadin wa azwajihi wa dhurriyyatihi kamabarakta 'ala `Ali Ibrahim innaka hamidun majid
Reference: Bukhari 6360