Prayer (Kitab Al-Salat): Details of Commencing Prayer

Dawud :: Book 3 : Hadith 885

Narrated Abdullah ibn Mas'ud:

The Prophet (peace_be_upon_him) said: When one of you bows, he should say three time,:"Glory be to my mighty Lord," and when he prostrates, he should say: "Glory be to my most high Lord" three times. This is the minimum number.