Sahih Muslim 908
صحيح مسلم#908SahihIbn Abi Laila reported:Ka'b b. 'Ujra met me and said: Should I not offer you a present (and added): The Messenger of Allah (ﷺ) came to us and we said: We have learnt how to invoke peace upon you; (kindly tell us) how we should bless you. He (the Holy Prophet) said: Say:" O Allah: bless Muhammad and his family as Thou didst bless the family of Ibrahim. Verily Thou art Praiseworthy and Glorious, O Allah
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 4:70