Angels speak on behalf of G-d - Key Passages
Tanakh consistently uses a style where the angel that is sent to the human to convey a message, speaks on behalf of G-d in a way that it seems like the angel has the power to make the promise happen. It almost seems G-d has come down to the human and is speaking to the human. These passages are telling that this is what G-d told me to tell you and it will happen. Genesis 16:10 And the angel of the Lord said to her , " I will greatly multiply your seed, and it will not be counted for abundance. " - This is the event where an angel makes a promise to multiply Hagar's seed on behalf of G-d. Genesis 18:1 Now the Lord appeared to him in the plains of Mamre , and he was sitting at the entrance of the tent when the day was hot. 2 And he lifted his eyes and saw, and behold, three men were standing beside him , and he saw and he ran toward them from the entrance of the tent, and he prostrated himself to the ground. 10 And he said, " I will surely return to you at this time ...