The Heights - 7:85
"And We sent to Median their brother Shu´ayb. He said: "O My people, worship Allah. You have no gods besides Him. A clear proof has come to you from your Lord. Measure and weigh exactly. Do not eat the people´s right. Do not make corruption in the earth after it has been leveled. This is better for you if you believe."
Shu'ayb's people took gods besides Allah:
Prophet Hud/11:87
"They said: "Shu´ayb, does your prayer require us to give up what our ancestors used to serve or to turn our trade as we wish? You are indeed mild-tempered and wise."