And make mention of the kinsman of `âd (- Hûd, a Messenger of God to them), when he warned his people (living) in wind-curved sand-dunes (in Hadzramût, south of Arabia) to whom Warners had already come before him and after him (saying), `Worship none but Allâh. I, indeed, fear lest the agony of a dreadful day should befall you.'