Surah Al-An'am 6:54

وَإِذَا جَآءَكَ ٱلَّذِينَ يُؤْمِنُونَ بِـَٔايَـٰتِنَا فَقُلْ سَلَـٰمٌ عَلَيْكُمْ ۖ كَتَبَ رَبُّكُمْ عَلَىٰ نَفْسِهِ ٱلرَّحْمَةَ ۖ أَنَّهُۥ مَنْ عَمِلَ مِنكُمْ سُوٓءًۢا بِجَهَـٰلَةٍ ثُمَّ تَابَ مِنۢ بَعْدِهِۦ وَأَصْلَحَ فَأَنَّهُۥ غَفُورٌ رَّحِيمٌ

And when those come to you who believe in Our verses, say, "Peace be upon you. Your Lord has decreed upon Himself mercy: that any of you who does wrong out of ignorance and then repents after that and corrects himself - indeed, He is Forgiving and Merciful."

Translation: Saheeh International

Tafsir

And when those who believe in Our signs come to you say to them ‘Peace be upon you. Your Lord has prescribed He has decreed for Himself mercy to the effect that truly innahu ‘truly’ may also be read as annahu ‘that’ as a substitution for al-rahma ‘mercy’ whoever of you does evil in ignorance of it when he did it and …

Excerpt from Tafsir al-Jalalayn, commentary on 6:54, via Quran.com. The reader has the full commentary and 9 more tafsirs.