And it is also authentically reported that he instructed people to offer this supplication after the tashahhud. Likewise, it is authentically reported that he would say after the tashahhud, before the closing salutation:

“O Allah, forgive my past and future sins, those I have concealed and those I have made known, and those You know better than I do. You are the One who brings forward and the One who holds back. There is no god but You.”

It is also authentically reported that Abū Bakr said, “O Messenger of Allah, teach me a supplication to offer during my prayer.”

He replied:

“Say: ‘O Allah, I have wronged myself a great deal, and none forgives sins but You. So grant me forgiveness from Yourself and have mercy on me. You are indeed the All-Forgiving, the Most Merciful.’”

Other authentic hadiths also report that he would supplicate after the tashahhud and before the closing salutation. He would supplicate while prostrating and, according to one narration, when he raised his head from bowing. He would also supplicate at the beginning of the prayer. No one, however, reported that he and those praying behind him would supplicate after the closing salutation. Rather, he would remember Allah by declaring that there is no deity worthy of worship except Allah, praising Him, glorifying Him, and proclaiming His greatness, as related in the authentic hadiths. And Allah knows best.

He was asked about someone who said:

“It is not permissible to supplicate except by the ninety-nine names. One must not say, ‘O Most Compassionate, O Bestower of Favors,’ nor say, ‘O Guide of the bewildered.’”

Is he entitled to say that?