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.

Though every sign should come to them, until they witness the painful chastisement.