2:199Al-Baqara

O people, seek repentance from Allah. Verily, I seek repentance from Him a hundred times a day.

When the Messenger of Allah (ﷺ) finished his prayer. He begged forgiveness three times and said: O Allah! Thou art Peace, and peace comes from Thee; Blessed art Thou, O Possessor of Glory and Honour. Walid reported: I said to Auza'i: How is the seeking of forgiveness? He replied: You should say: I beg forgiveness from Allah, I beg forgiveness from Allah."

When the Messenger of Allah (ﷺ) intended to get up from the assembly he used to say in the last. Glory be to Thee. O Allah, and I begin with praise of Thee, I testify that there is no god but Thou; I ask Thy pardon, and return to Thee in repentance. The man asked: Messenger of Allah! you utter the words now which you did not do in the past? He replied: (This is an) atonement for what takes place in the assembly.

"The Messenger of Allah said: 'Whoever leaves his house for the prayer and says: 'Allahumma inni asa'luka bi-haqqis-sa'ilina 'alaika, wa as'aluka bi-haqqi mamshaya hadha, fa inni lam akhruj asharan wa la batran, wa la riya'an, wa la sum'atan, wa kharajtu-ttiqa'a sukhtika wabtigha'a mardatika, fa as'aluka an tu'idhani minan-nari wa an taghfira li dhunubi, Innahu la yaghfirudh-dhunuba illa Anta. (O Allah, I ask You by the right that those who ask of You have over You, and I ask by virtue of this walking of mine, for I am not going out because of pride or vanity, or to show off or make a reputation, rather I am going out because I fear Your wrath and seek Your pleasure. So I ask You to protect me from the Fire and to forgive me my sins, for no one can forgive sins except You),' Allah will turn His Face towards him and seventy thousand angels will pray for his forgiveness."

“The pilgrims performing Hajj and ‘Umrah are a delegation to Allah. If they call upon Him, He will answer them; and if they ask for His forgiveness, He will forgive them.”