He [Angel Gabriel] said, “I am only the messenger of your Lord to give you [news of] a pure boy.” She (Mary) said, “How can I have a boy while no man has touched me and I have not been unchaste?” He said, “Thus [it will be]; your Lord says, ‘It is easy for Me, and We will make him a sign to the people and a mercy from Us. And it is a matter [already] decreed.'”
(Maryam 19:19-21)