Awn bin 'Abdullah bin 'Utba عون بن عبد الله بن عتبة بن مسعود الهذلي · The Book on Salat (Prayer)

the Prophet said: "When one of you bows then says while he is bowing: (Subhana Rabbiyal Azim) 'Glorious is my Lord the Magnificent' three times, then he has completed his bowing. And that is the least of it. And when he prostrates and says while prostrating: (Subhana Rabbiyal A'la) 'Glorious is my Lord the Most High' three times, then he has completed his prostrations, and that is the least of it.'"