Sunnah of Hope and Forgiveness for doing many many Sins so read daily 3 minimum, you may read more 7 or 11 or 100 times.
A person who says: “Astaghfirullahal-’Azeemal-lazi la ilaha illa Huwal-Hayyul-Qayyum wa atubu ilayh ”
Meaning: I seek the forgiveness of Allah the Mighty, Whom there is none worthy of worship except Him, The Living, The Eternal, and I repent unto Him"
Even if he has committed Sins as much as the the foam of an ocean, still he will be forgiven. Hadith