18:104
ٱلَّذِينَ ضَلَّ سَعْيُهُمْ فِى ٱلْحَيَوٰةِ ٱلدُّنْيَا وَهُمْ يَحْسَبُونَ أَنَّهُمْ يُحْسِنُونَ صُنْعًا
alladhīna ḍalla saʿyuhum fī l-ḥayati l-dun'yā wahum yaḥsabūna annahum yuḥ'sinūna ṣun'ʿan
[They are] those whose effort is lost in worldly life, while they think that they are doing well in work."
— Saheeh International
whose efforts in this world are misguided, even when they think they are doing good work?
— M. A. S. Abdel Haleem
"Those whose efforts have been wasted in this life while they thought that they were acquiring good by their deeds.
— Muhammad Muhsin Khan & Muhammad Taqi-ud-Din al-Hilali