Narrated Ka`b bin Ujra:
It was said, "O Allah's Messenger (ﷺ)! We know how to greet you, but how to invoke Allah for you?" The Prophet said, "Say: Allahumma salli ala Muhammadin wa'ala `Ali Muhammaddin, kama sallaita 'ala all Ibrahim, innaka Hamidun Majid." (DE)
USC-MSA web (English) reference: Vol. 6, Book 60, Hadith 320 (DE)
Arabic reference (DE): Book 65, Hadith 4797 (DE)