Surah Hud — Ayah 26 (11:26)
أَن لَّا تَعۡبُدُوٓاْ إِلَّا ٱللَّهَۖ إِنِّيٓ أَخَافُ عَلَيۡكُمۡ عَذَابَ يَوۡمٍ أَلِيمٖ ٢٦
English translation (Saheeh International)
That you not worship except Allāh. Indeed, I fear for you the punishment of a painful day."
Brief commentary
Noah called his people to worship Allah alone, and not to worship any besides Him, because he feared the punishment of a painful day for them.