Matthew 1:20, 21, 22

As he considered this, an angel of the Lord appeared to him in a dream. “Joseph, son of David,” the angel said, “do not be afraid to take Mary as your wife. For the child within her was conceived by the Holy Spirit.

And she will have a son, and you are to name him Jesus, for he will save his people from their sins.”

All of this occurred to fulfill the Lord’s message through his prophet