O People of the Scripture. do not commit excess in your religion or say about Allah except the truth. The Messiah, Jesus, the son of Mary, was but a messenger of Allah and His word which He directed to Mary and a soul [created at a command] from Him. So believe in Allah and His messengers. And do not say, "Three"; desist - it is better for you. Indeed, Allah is but one God. Exalted is He above having a son. To Him belongs whatever is in the heavens and whatever is on the earth. And sufficient is Allah as Disposer of affairs.

— 

Quran 4 (An-Nisa), ayat 171[3]

They have certainly disbelieved

who say, " Allah is the Messiah,the son of Mary" while the Messiah has said, "O Children of Israel, worship Allah, my Lord and your Lord." Indeed, he who associates others with Allah - Allah has forbidden him Paradise, and his refuge is the Fire. And there are not for the wrongdoers any helpers. They have certainly disbelieved who say, " Allah is the third of three." And there is no god except one God. And if they do not desist from what they are saying, there will surely afflict the disbelievers among them a painful punishment. So will they not repent to Allah and seek His forgiveness? And Allah is Forgiving and Merciful. The Messiah, son of Mary, was not but a messenger; [other] messengers have passed on before him. And his mother was a supporter of truth. They both used to eat food. Look how We make clear to them the signs; then look how they are deluded.

— 
Quran 112 (Al-Ikhlas), ayat 1-4[8]

And [beware the Day] when Allah

will say, "O Jesus, Son of Mary, did you say to the people, 'Take me and my mother as deities besides Allah ?'" He will say, "Exalted are You! It was not for me to say that to which I have no right. If I had said it, You would have known it. You know what is within myself, and I do not know what is within Yourself. Indeed, it is You who is Knower of the unseen. I said not to them except what You commanded me - to worship Allah, my Lord and your Lord. And I was a witness over them as long as I was among them; but when You took me up, You were the Observer over them, and You are, over all things, Witness. If You should punish them - indeed they are Your servants; but if You forgive them - indeed it is You who is the Exalted in Might, the Wise.
— Quran 5 (Al-Ma'ida), ayat 116-118[5]

And they say, "The Most Merciful has taken [for Himself] a son." You have done an atrocious thing. The heavens almost rupture therefrom and the earth splits open and the mountains collapse in devastation that they attribute to the Most Merciful a son. And it is not appropriate for the Most Merciful that He should take a son. There is no one in the heavens and earth but that he comes to the Most Merciful as a servant.
— Quran 19 (Maryam (sura)), ayat 88-93[6]

Allah has not taken any son, nor has there ever been with Him any deity. [If there had been], then each deity would have taken what it created, and some of them would have sought to overcome others. Exalted is Allah above what they describe [concerning Him].
— Quran 23 (Al-Mumenoon), ayat 91[7]

Say: He is Allah, the One and Only; Allah, the Eternal, Absolute; He begetteth not, nor is He begotten; And there is none like unto Him.

— Quran 112 (Al-Ikhlas), ayat 1-4[8]