Prophet Abraham - 14:52 This is a warning to the people. That they may listen to this warning and know that He is the only God, and that those who have understanding may take counsel.
All messengers conveyed the common message, "Serve Allah alone."
The Cow/2:133 "If you had been witnesses when Jacob died. He asked his children, "Whom will you serve after me?"They said, "We will serve the only God, the God of your God and the God of your fathers Abraham, Ishmael and Isaac, and to Him we are the submissive ones."

The Table Spread/5:117 I said to them nothing but what You commanded me: ´Serve Allah, my Lord and your Lord.´ I was a witness to them as long as I was among them, and when You took my life, You became a watcher over them. You are the Witness of all things.
The Table Spread/5:116 "Allah will say: "O Jesus son of Mary, did you say to the people, ´Take me and my mother as gods besides Allah´?"(Jesus) will reply: "You are great, it is not befitting me to say what I have no right to say. You would have known if I had said such a thing. You know what I think, but I do not know what you think. You know all mysteries."

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."
The Heights/7:73 "And We sent to the people of Thamud their brother Salih: "O My people, worship Allah. You have no god besides Him. A clear proof has come to you from your Lord, and this camel of Allah will be a sign for you. Let him graze on Allah´s land. Do not harm him, lest a painful torment seizes you."

The Spider/29:16 "And Abraham. He said to his people, "Serve Allah and listen to Him with reverence. That is better for you if you know."

The Heights/7:65 "And We sent to the people of Ad their brother Hud, saying: "My people, worship Allah. You have no god but Him. Will you not be righteous?"
The Heights/7:59 "We sent Noah to his people: "O my people, worship Allah. You have no god besides Him. I fear for you the torment of a great day."

The Believers/23:32 "We sent to them a messenger from among them: "Serve Allah, you have no god but Him. Will you not show respect and act righteously?"

The Bee/16:36 "And We sent a messenger among every people, saying, "Serve Allah and beware of idolatry."Some of them were guided by Allah, and some of them were condemned to remain in error. Travel through the earth and see how was the end of those who denied."

The Prophets/21:25 "We did not send a messenger before you except that We revealed to him, "There is no god but Me; serve Me alone."