'Angel of the Lord' in the Bible

But while he thought on these things, lo! an angel of the Lord appeared to him in a dream, saying, Joseph, son of David, fear not to take to thee Mary thy wife; for that which is conceived in her is by the Holy Spirit.

Then Joseph, on waking up from sleep, did as the angel of the Lord had bidden him, and took to him his wife;

And when they had gone, lo! an angel of the Lord appeareth to Joseph in a dream, saying, Arise, and take the child and his mother, and flee into Egypt, and remain there until I speak to thee; for Herod will seek the child, to destroy him.

But when Herod was dead, lo! an angel of the Lord appeareth in a dream to Joseph in Egypt,

And, lo! there was a great earthquake; for an angel of the Lord descended from heaven, and came and rolled away the stone, and sat upon it.