'Angel of the Lord' in the Bible

But when he thought about these things, behold, an angel of the Lord appeared to him in a dream, saying, "Joseph, son of David, don't be afraid to take to yourself Mary, your wife, for that which is conceived in her is of the Holy Spirit.

Joseph arose from his sleep, and did as the angel of the Lord commanded him, and took his wife to himself;

Now when they had departed, behold, an angel of the Lord appeared to Joseph in a dream, saying, "Arise and take the young child and his mother, and flee into Egypt, and stay there until I tell you, for Herod will seek the young child to destroy him."

But when Herod was dead, behold, an angel of the Lord appeared in a dream to Joseph in Egypt, saying,

Behold, there was a great earthquake, for an angel of the Lord descended from the sky, and came and rolled away the stone from the door, and sat on it.