And to Midian (We had sent) their brother Shuaib, he said, “”O my people! serve Allah, you have no god other that Him. Clear proof has come to you from your Fosterer so give back full measure and weight, and (with regard to) goods, do not give to people anything which is less than what is due to them, and do not cause corruption in the earth after it has been set right. That is the best for you if you are believers.
Shuaib (PBH) had invited their people to serve (worship) Allah (SWT) besides whom there is no god and to give up the evil they were involved in. Those who obeyed them were delivered and those who rejected them were punished through various natural calamities.
