When Mary the Mother of Jesus had been betrothed to Joseph, before they came together, she was found to be with child by the Holy Spirit. But Joseph her husband, being a just man, and not wishing to expose her to reproach, was minded to put her away privately. But while he thought on these things, behold, an angel of the Lord appeared to him in a dream, saying, Do not be afraid, Joseph, son of David, to take to you Mary your wife, for that which is begotten in her is of the Holy Spirit. And she shall bring forth a Son, and you shall call His name Jesus; for He shall save His people from their sins.

-Matthew 1:18-21