Narrated by Abdur-Rahman bin Abi Laila (ra):
Kab bin Ujrah met me and said, “Shall I not give you a present I got from the Prophet?” `Abdur- Rahman said, “Yes, give it to me.” I said, “We asked Allah’s Messenger (ﷺ) saying, ‘O Allah’s Messenger (ﷺ)! How should one (ask Allah to) send blessings on you and the members of the family, for Allah has taught us how to salute you (in the prayer)?’ He said, ‘Say:

O Allah! Send Your Prayers on Muhammad and on the family of Muhammad, as You sent Your Prayers on Abraham and on the family of Abraham, for You are the Most Praise-worthy, the Most Glorious. O Allah! Send Your Blessings on Muhammad and the family of Muhammad, as You sent your Blessings on Abraham and on the family of Abraham, for You are the Most Praise-worthy, the Most Glorious.’ “

اللَّهُمَّ صَلِّ عَلَى مُحَمَّدٍ، وَعَلَى آلِ مُحَمَّدٍ، كَمَا صَلَّيْتَ عَلَى إِبْرَاهِيمَ وَعَلَى آلِ إِبْرَاهِيمَ، إِنَّكَ حَمِيدٌ مَجِيدٌ، اللَّهُمَّ بَارِكْ عَلَى مُحَمَّدٍ، وَعَلَى آلِ مُحَمَّدٍ، كَمَا بَارَكْتَ عَلَى إِبْرَاهِيمَ، وَعَلَى آلِ إِبْرَاهِيمَ، إِنَّكَ حَمِيدٌ مَجِيدٌ ‌‏

Allahumma Salli Ala Muhammadin Wa Ala Aali Muhammadin Kamaa Sallaita Ala Ibrahima Wa Ala Aali Ibrahima Innaka Hamidum Majid. Allahumma Baarik Ala Muhammadin Wa Ala Aali Muhammadin Kamaa Baarakta Ala Ibrahima Wa Ala Aali Ibrahima Innaka Hamidum Majid

Sahih al-Bukhari 3370