Allah, the Exalted, says,
(And) This is an introductory to what is implied: "Verily, We sent."
(to the `Ad (people) their brother Hud.) Hud came to them commanding them to worship Allah alone, without any associates. He forbade them from worshipping the idols which they made up, inventing names as gods. He informed them that he did not want any reward from them for his sincere advising and conveying of Allah's Message. He only sought his reward from Allah, the One Who created him.
(Will you not then understand) Someone has come calling you to what will benefit your situation in this life and the Hereafter without asking for any wage (from them). Then he commanded them to seek the forgiveness of the One Who is capable of expiating previous sins. He also commanded them to repent for that which they may do in the future. Whoever has these characteristics, Allah will make his sustenance easy for him, grant him ease in his affairs and guard over his situation. For this reason Allah says,
(He will send you (from the sky) abundant rain,)