Abu Mas'ud Al-Badri (May Allah be pleased with him) reported:
We were sitting in the company of Sa'd bin 'Ubadah (May Allah be pleased with him), when the Messenger of Allah (ﷺ) came to us. Bashir bin Sa'd said: "O Messenger of Allah! Allah has commanded us to supplicate for you, but how should we do that?" The Messenger of Allah (ﷺ) kept silent. We were much perturbed over his silence and we wished he did not asked him this question. The Messenger of Allah (ﷺ) said, "Say: 'O Allah, exalt the mention of Muhammad and the family of Muhammad as you exalted the family of Ibrahim. And bless Muhammad and the family of Muhammad as You blessed the family of Ibrahim. You are the Praised, the Glorified,' and the method of greeting (i.e., Salam) is as you know."[Muslim].
App reference: Book 15, Hadith 10
Arabic/English book reference: Book 15, Hadith 1406