'Angel of the Lord' in the Bible

but while he pondered on these things, behold, 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 begotten in her is of the Holy Spirit.

But Joseph, having awoke up from his sleep, did as the angel of the Lord had enjoined him, and took to him his wife,

Now, they having departed, behold, an angel of the Lord appears in a dream to Joseph, saying, Arise, take to thee the little child and his mother, and flee into Egypt, and be there until I shall tell thee; for Herod will seek the little child to destroy it.

But Herod having died, behold, an angel of the Lord appears in a dream to Joseph in Egypt, saying,

And behold, there was a great earthquake; for an angel of the Lord, descending out of heaven, came and rolled away the stone and sat upon it.