Surah Al-Ahqaf 46:21

۞ وَٱذْكُرْ أَخَا عَادٍ إِذْ أَنذَرَ قَوْمَهُۥ بِٱلْأَحْقَافِ وَقَدْ خَلَتِ ٱلنُّذُرُ مِنۢ بَيْنِ يَدَيْهِ وَمِنْ خَلْفِهِۦٓ أَلَّا تَعْبُدُوٓا۟ إِلَّا ٱللَّهَ إِنِّىٓ أَخَافُ عَلَيْكُمْ عَذَابَ يَوْمٍ عَظِيمٍ

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."

Translation: Saheeh International

Tafsir

And mention the brother of ‘Ād namely Hūd peace be upon him when idh … from here to the end of the verse constitutes an inclusive substitution he warned his people he threatened them at Ahqāf ‘the Sand dunes’ is the name of a valley in Yemen where their dwellings were located — and already warners messengers had …

Excerpt from Tafsir al-Jalalayn, commentary on 46:21, via Quran.com. The reader has the full commentary and 9 more tafsirs.