The Prophet ﷺ said, "When one of you bows and says during his bowing, 'Glory be to my Lord the Magnificent,' three times, his bowing is complete, and that is the minimum. When he prostrates and says during his prostration, 'Glory be to my Lord the Most High,' three times, his prostration is complete, and that is the minimum."
حدثنا علي بن حجر أخبرنا عيسى بن يونس عن ابن أبي ذئب عن إسحق بن يزيد الهذلي عن عون بن عبد الله بن عتبة
أن النبي ﷺ قال إذا ركع أحدكم فقال في ركوعه سبحان ربي العظيم ثلاث مرات فقد تم ركوعه وذلك أدناه وإذا سجد فقال في سجوده سبحان ربي الأعلى ثلاث مرات فقد تم سجوده وذلك أدناه
[Its chain is daif]. Abu Dawud (886) and Ibn Majah (890) also reported it through Ibn Abu Dhib with the same chain, and Abu Dawud said, this is mursal, Awn did not meet Abdullah.On this topic there are also narrations from Huzaifa [to come at 262, and Ibn Majah, 888] and Uqba bin Amir [Abu Dawud, 869, and Ibn Majah, 887].