Sayyidul Istighfar — The Master Supplication for Forgiveness
Where this dua comes from
This is called Sayyidul Istighfar — "the master (or best) of seeking forgiveness" — a name that comes directly from the hadith itself, where the Prophet ﷺ describes it that way and adds that whoever recites it during the day with certainty and dies that day before evening, or recites it at night with certainty and dies before morning, enters Paradise. Structurally, it's unusual among the adhkar for how much it packs into one sentence: an acknowledgment of Allah's lordship, an admission of one's own status as a created servant, a statement of ongoing (if imperfect) commitment, a request for refuge from one's own wrongdoing, and finally the forgiveness request itself, framed around acknowledging both Allah's favor and one's own fault side by side. Its length and density are why it's usually recited slowly and deliberately rather than as a quick daily line.
When to recite
Morning and evening, as part of the daily adhkar.