Fiqh-us-Sunnah Volume 1, Purification and Prayer, Fiqh 1.148.

It is preferred to remember Allah with the following words, “Subhana Rabiyy al-‘Azheem (Glory to my Lord, the Great.)” Reported ‘Uqbah ibn ‘Amr, “When ‘Glorify the name of your Lord, the Great,’ was revealed, the Prophet told us, ‘Do so in your bowings.” This is related by Ahmad, Abu Dawud and others with a good chain.

Reported Huzhaifah, “I prayed with the Messenger of Allah, upon whom be peace, and while bowing he would say, ‘Subhana Rabiyy al-‘Azheem.” (Related by Muslim, Abu Dawud, an-Nasa’i, at-Tirmizhi and Ibn Majah.)

The phrase Subhana Rabiyy al-‘Azheem wa bihamdihi has been related through a number of chains, but all of them are weak. Ash-Shaukani maintains, “The different chains support each other. It is perfectly acceptable for one who is praying to limit himself to Subhana Rabiyy al-‘Azheem or to add one of the following:

1. ‘Ali reported that while bowing, the Messenger of Allah, upon whom be peace, would say, “O Allah, for You have I bowed, and it is You that I have believed in and to You have I submitted. You are my Lord. My hearing, sight, marrow, bones and nerves and what is carried by my feet are for Allah, the Lord of the Worlds.” (Related by Ahmad, Muslim, Abu Dawud and others.)

2. ‘Aishah reported that while bowing and prostrating, the Messenger of Allah, upon whom be peace, would say, “Glorified and Holy are You, Lord of the angels and the souls.”

3. Reported ‘Auf ibn Malik, “I prayed with the Messenger of Allah one night. He recited al-Baqarah and while bowing said, ‘Glory be to the One of Omnipotence, the Master of the dominions, of grandeur and of honour.”‘ (Related by Abu Dawud, at-Tirmizhi and an-Nasa’i.)

4. ‘Aishah said that when the Prophet, upon whom be peace, bowed or prostrated, he would often say, “Glory and praise be to You, O Allah, our Lord. O Allah, forgive me.” This was how he applied the Qur’an. (Related by Ahmad, al-Bukhari, Muslim and others.)