The first kind includes the first half of al-Fātihah, as well as:

“Glory be to You, O Allah, and praise be to You. Blessed is Your name, exalted is Your majesty, and there is no god but You.”

It also includes glorifying Allah when bowing and prostrating.

The second kind includes his words:

“I have turned my face toward Him who created the heavens and the earth,”

and his words when bowing and prostrating:

“O Allah, to You I have bowed and to You I have prostrated,”

as in the hadith of ‘Alī narrated by Muslim.

The third kind includes his words:

“O Allah, put distance between me and my sins,”

and his supplications when bowing and prostrating. For this reason, a group of Ahmad’s followers deemed forms of praise obligatory, just as they deemed the opening supplication obligatory. Two positions on this have been reported from Ahmad, and Ibn Battah and others favoured the view that it is obligatory. A detailed discussion of this belongs elsewhere.

The point here is that occasionally using a less preferred form—such as the opening supplication narrated by Abū Hurayrah, or opening with “I have turned my face” or “Glory be to You, O Allah,” according to those who prefer the alternative—is better than consistently using one form and abandoning another. This is because the best guidance is the guidance of Muhammad, may Allah bless him and grant him peace. As established in an authentic hadith, he used to say in his Friday sermon:

“The best speech is the speech of Allah, and the best guidance is the guidance of Muhammad, may Allah bless him and grant him peace.”

He certainly did not invariably use a single opening supplication, for the hadith of Abū Hurayrah indicates that he used to begin with this one.