Musannaf Ibn Abi Shaybah

Ibrahim says that if a person, at the beginning of the prayer, says Subhan Allah, Allahu Akbar, or La ilaha illallah, it is permissible. And there are two prostrations for forgetfulness.

Hazrat Hakam states that if, at the beginning of the prayer, one says "Subhan Allah" or "La ilaha illallah," then these words will serve in place of "Allahu Akbar."

Hazrat Abu Alia was asked, "With which words did the prophets begin their prayer?" He replied, "They used to begin the prayer with words of monotheism, glorification, and declaration of God's oneness."

Hazrat Sha'bi says that if you begin the prayer with any of the names of Allah Almighty, it is permissible.