Таргум к Берешит 18:2

And he lifted up his eyes and looked, and, behold, three angels in the resemblance of men were standing before him; (angels) who had been sent from the necessity of three things;--because it is not possible for a ministering angel to be sent for more than one purpose at a time;--one, then, had come to make known to him that Sarah should bear a man-child; one had come to deliver Lot; and one to overthrow Sedom and Amorah. And when he saw them, he ran to meet them from the door of the tent, and bowed himself on the earth.

Three angels were sent to our father Abraham; and the three were sent for three things; because it is not possible that one of the high angels should be sent for more things than one. The first angel was sent to announce to our father Abraham, that, behold, Sarah would bear Izhak; the second angel was sent to deliver Lot from the midst of the overthrow; the third angel was sent to overthrow Sedom and Amorah, Admah and Zeboim. Therefore was there a word of prophecy from before the Lord unto Abraham the Just, and the Word of the Lord was revealed to him in the valley of vision; and he sat in the door of the tabernacle, comforting himself from his circumcision in the fervour (or strength) of the day.