Matthew 1:18-25  NAS          

Now the birth of Jesus Christ was as follows:  when His mother Mary had been betrothed to Joseph, before they came together she was found to be with child by the Holy Spirit.  And Joseph her husband , being a righteous man and not wanting to disgrace her, planned to send her away secretly.  But when he had considered this, behold, and an angel of the Lord appeared to him in a dream, saying, "Joseph, son of David, do not be afraid to take Mary as your wife; for the Child who has been conceived in her is of the Holy Spirit.  She will bear a Son; and you shall call His name Jesus, for He will save His people from their sins."  Now all this took place to fulfill what was spoken by the Lord through the prophet:  "BEHOLD, THE VIRGIN SHALL BE WITH CHILD AND SHALL BEAR A SON, AND THEY SHALL CALL HIS NAME IMMANUEL," which translates means, "'GOD WITH US."  And Joseph awoke from his sleep and did as the angel of the Lord commanded him, and took Mary as his wife, but kept her a virgin until she gave birth to a Son; and he called His name Jesus.