When the Prophet (ﷺ) uttered salutation at the end of the prayer, he used to say: "O Allah, forgive me my former and latter sins, what I have kept secret and what I have done openly, and what I have done extravagance; and what You know better than I do. You are the Advancer, the Delayer, there is no god but You."
Sunan Abi Dawud Book 8, Hadith 94
← Previous Hadith I heard the Messenger of Allah (ﷺ) saying (the version of Sulayman has: The Messenger of Allah (ﷺ) used to say) after his prayer:-

"O Allah, our Lord and Lord of everything, I bear witness that Thou art the Lord alone Who hast no partner; O Allah, Our Lord and Lord of everything, I bear witness that Muhammad is Thy servant and Thy apostle ; O Allah, our Lord and Lord of everything, I bear witness that all the servants are brethren; O Allah, our Lord and Lord of everything make me sincere to Thee, and my family too at every moment, in this world and in the world hereafter, O Possessor of glory and honour, listen to me and answer. Allah is incomparably great. O Allah, Light of the heavens and of the earth".

The narrator Sulaiman b. Dawud said: "Lord of the heavens and of the earth, Allah is incomparably great. Allah is sufficient for me; and the excellent guardian is He; Allah is incomparably great.

Sunan Abi Dawud Book 8, Hadith 93 Next Hadith → The Prophet (ﷺ) used to supplicate Allah: "My Lord, help me and do not give help against me; grant me victory, and do not grant victory over me; plan on my behalf and do not plan against me; guide me, and made my right guidance easy for me; grant me victory over those who act wrongfully towards me; O Allah, make me grateful to Thee, mindful of Thee, full of fear towards Thee, devoted to Thy obedience, humble before Thee, or penitent. My Lord, accept my repentance, wash away my sin, answer my supplication, clearly establish my evidence, guide my heart, make true my tongue and draw out malice in my breast."

Sunan Abi Dawud Book 8, Hadith 95