Holy Qur’an, Ch 4-WOMEN, v 171:
O People of the Book! Do not go to extremes in your religion: nor say of Allah anything but the truth. Verily, Christ1 Jesus the son of Mary was no more than a messenger of Allah, and His Word which he bestowed upon Mary, And a Spirit proceeding from Him: so believe in Allah and his messengers. Say not "Trinity": desist: it will be better for you: For your Allah is One God: Glory be to Him: (Far Exalted is He) above having a son. To Him belongs all things in the heavens and the earth. And enough is Allah as a Disposer of affairs.