And those who have no knowledge say: Why does not Allah speak to us or a sign come to us? Even thus said those before them, the like of what they say; their hearts are all alike. Indeed We have made the communications clear for a people who are sure.

And to Samood (We sent) their brother Salih. He said: O my people! serve Allah, you have no god other than Him; clear proof indeed has come to you from your Lord; this is (as) Allah's she-camel for you-- a sign, therefore leave her alone to pasture on Allah's earth, and do not touch her with any harm, otherwise painful chastisement will overtake you.