Qur'an 39:56

أَن تَقُولَ نَفْسٌ يَـٰحَسْرَتَىٰ عَلَىٰ مَا فَرَّطتُ فِى جَنۢبِ ٱللَّهِ وَإِن كُنتُ لَمِنَ ٱلسَّـٰخِرِينَ

“Lest a soul should say, "Oh, [how great is] my regret over what I neglected in regard to Allāh and that I was among the mockers."”

Az-Zumar 39:56 · Saheeh International