Surah Az-Zumar 39:56
أَن تَقُولَ نَفْسٌ يَٰحَسْرَتَىٰ عَلَىٰ مَا فَرَّطتُ فِى جَنۢبِ ٱللَّهِ وَإِن كُنتُ لَمِنَ ٱلسَّٰخِرِينَ ٥٦
EnglishSahih International
Lest a soul should say, "Oh [how great is] my regret over what I neglected in regard to Allah and that I was among the mockers."