Quran 6:54 from Surah Al-An'aam on Divine Marvels.
وَإِذَا جَآءَكَ ٱلَّذِينَ يُؤۡمِنُونَ بِـَٔايَٰتِنَا فَقُلۡ سَلَٰمٌ عَلَيۡكُمۡۖ كَتَبَ رَبُّكُمۡ عَلَىٰ نَفۡسِهِ ٱلرَّحۡمَةَ أَنَّهُۥ مَنۡ عَمِلَ مِنكُمۡ سُوٓءَۢا بِجَهَٰلَةٖ ثُمَّ تَابَ مِنۢ بَعۡدِهِۦ وَأَصۡلَحَ فَأَنَّهُۥ غَفُورٞ رَّحِيمٞ
English translation: And when come to you those who believe in Our Verses then say Peace (be) upon you (Has) Prescribed your Lord upon Himself the Mercy that he who does among you evil in ignorance then repents from after it and reforms then, indeed He (is) Oft-Forgiving Most Merciful
Transliteration: wa-idha jaaka alladhina yu'minuna biayatina faqul salamun alaykum kataba rabbukum ala nafsihi al-rahmata annahu man amila minkum suan bijahalatin thumma taba min ba'dihi wa-aslaha fa-annahu ghafurun rahimun