'Angel of the Lord' in the Bible

Now the angel of the Lord found her by a spring of water in the wilderness, by the spring on the way to Shur.

Then the angel of the Lord said to her, “Return to your mistress, and submit yourself to her authority.”

Moreover, the angel of the Lord said to her, “I will greatly multiply your descendants so that they will be too many to count.”

The angel of the Lord said to her further,“Behold, you are with child,And you will bear a son;And you shall call his name Ishmael,Because the Lord has given heed to your affliction.

But the angel of the Lord called to him from heaven and said, “Abraham, Abraham!” And he said, “Here I am.”

Then the angel of the Lord called to Abraham a second time from heaven,