Surah Al-Ahqaf, Verse 21

۞ وَٱذۡكُرۡ أَخَا عَادٍ إِذۡ أَنذَرَ قَوۡمَهُۥ بِٱلۡأَحۡقَافِ وَقَدۡ خَلَتِ ٱلنُّذُرُ مِنۢ بَيۡنِ يَدَيۡهِ وَمِنۡ خَلۡفِهِۦٓ أَلَّا تَعۡبُدُوٓاْ إِلَّا ٱللَّهَ إِنِّيٓ أَخَافُ عَلَيۡكُمۡ عَذَابَ يَوۡمٍ عَظِيمٖ٢١

wa-udh'kur akhā ʿādin idh andhara qawmahu bil-aḥqāfi waqad khalati l-nudhuru min bayni yadayhi wamin khalfihi allā taʿbudū illā l-laha innī akhāfu ʿalaykum ʿadhāba yawmin ʿaẓīmin

And mention, [O Muḥammad], the brother of ʿAad, when he warned his people in [the region of] al-Aḥqāf - and warners had already passed on before him and after him - [saying], "Do not worship except Allāh. Indeed, I fear for you the punishment of a terrible day."