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 passed away before him and after him that is to say before Hūd came to them and after him to their peoples — saying ‘Do not worship anyone but God the statement beginning with wa-qad khalat ‘and already warners had passed away’ is a parenthetical one. Truly I fear for you — should you worship other than God — the chastisement of a dreadful day’.