'Angel of the Lord' in the Bible

And an angel of the Lord came to her by a fountain of water in the waste land, by the fountain on the way to Shur.

And the angel of the Lord said, Your seed will be greatly increased so that it may not be numbered.

And the angel of the Lord said, See, you are with child and will give birth to a son, to whom you will give the name Ishmael, because the ears of the Lord were open to your sorrow.

But the voice of the angel of the Lord came from heaven, saying, Abraham, Abraham: and he said, Here am I.

And the voice of the angel of the Lord came to Abraham a second time from heaven,

And in my dream the angel of the Lord said to me, Jacob: and I said, Here am I.