Surah Hud, Verse 26
أَن لَّا تَعْبُدُوٓا۟ إِلَّا ٱللَّهَ ۖ إِنِّىٓ أَخَافُ عَلَيْكُمْ عَذَابَ يَوْمٍ أَلِيمٍۢ
Translation — Sahih International
That you not worship except Allah. Indeed, I fear for you the punishment of a painful day."
Source
Kur'an-ı Kerim, Hûd Suresi 11:26
https://kuran.diyanet.gov.tr/mushaf/kuran-meal-2/11-suresi-26-ayet