Surah Al-Kahf 18:104
ٱلَّذِينَ ضَلَّ سَعْيُهُمْ فِى ٱلْحَيَوٰةِ ٱلدُّنْيَا وَهُمْ يَحْسَبُونَ أَنَّهُمْ يُحْسِنُونَ صُنْعًا ١٠٤
EnglishSahih International
[They are] those whose effort is lost in worldly life, while they think that they are doing well in work."