Narrated `Abdur-Rahman bin Abi Laila:
Ka`b 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, the members of the family, for Allah has taught us how to salute you (in the prayer)?' He said, 'Say:

Translation:
O Allah! Send Your Mercy on Muhammad and on the family of Muhammad, as You sent Your Mercy 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.

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 (ﷺ) said, "Say:

Narrated Abu Sa`id Al-Khudri:
We said, "O Allah's Messenger (ﷺ)! This is (i.e. we know) the greeting to you; will you tell us how to send Salat on you?" He (ﷺ) said,

Translation:
'O Allah! Send Your Salat (Blessings) on Muhammad, Your slave and Your Messenger as You sent Your Salat on Ibrahim, and send Your Blessings on Muhammad and his family as You sent Your Blessings on (Prophet) Ibrahim and Ibrahim's family.

Narrated Abu Humaid As-Sa`idi:
The people asked, "O Allah's Messenger (ﷺ)! How shall we (ask Allah to) send blessings on you?" Allah's Apostle (ﷺ) replied, "Say:

Translation:
O Allah! Send Your Mercy on Muhammad and on his wives and on his off spring, as You sent Your Mercy on Abraham's family; and send Your Blessings on Muhammad and on his offspring, as You sent Your Blessings on Abraham's family, for You are the Most Praiseworthy, the Most Glorious.