When you know it was your own doing
The first words spoken by a human being after the first mistake.
قَالَا رَبَّنَا ظَلَمْنَآ أَنفُسَنَا وَإِن لَّمْ تَغْفِرْ لَنَا وَتَرْحَمْنَا لَنَكُونَنَّ مِنَ ٱلْخَـٰسِرِينَ
Rabbanā ẓalamnā anfusanā, wa in lam taghfir lanā wa tarḥamnā la-nakūnanna mina-l-khāsirīn.
They said, "Our Lord, we have wronged ourselves, and if You do not forgive us and have mercy upon us, we will surely be among the losers."
Where this comes from
Iblīs argued when he was told he had erred. Ādam ﷺ did not. This is the difference the Qur'an draws between the two, and it is the whole of repentance in one line.
Source
The Qur'an · 7:23
Qur'an
- Qur'anic text in the Uthmani script via Quran.com; translation: Saheeh International