Quran 39:56 from Surah Az-Zumar on Divine Marvels.
أَن تَقُولَ نَفۡسٞ يَٰحَسۡرَتَىٰ عَلَىٰ مَا فَرَّطتُ فِي جَنۢبِ ٱللَّهِ وَإِن كُنتُ لَمِنَ ٱلسَّٰخِرِينَ
English translation: Lest should say a soul Oh! My regret over what I neglected in regard to Allah and that I was surely among the mockers
Transliteration: an taqula nafsun yahasrata ala ma farrattu fi janbi al-lahi wa-in kuntu lamina al-sakhirina