Rashi on Numbers 22:22/רש"י על במדבר כ״ב:כ״ב

1כי הולך הוא [AND GOD'S ANGER WAS KINDLED] BECAUSE HE WENT — He perceived that the matter was evil in the eyes of the Omni-present and yet he longed to go.

2לשטן לו [AND THE ANGEL OF THE LORD STOOD IN THE WAY] FOR AN OBSTRUCTION AGAINST HIM — It was an Angel of Mercy מלאך ה׳, an angel of the Lord,( the designation of God as a God of Mercy), and he wished to deter him from sinning — so that he should not sin and perish (Midrash Tanchuma, Balak 8).

3ושני נעריו עמו AND HIS TWO LADS WERE WITH HIM — From here we have a rule for a distinguished personage who is going on a journey, that he should take with him two men to serve him, so that these in turn may serve one another (i.e., act for one another by taking over the other’s duties if he must leave his master for a short time) (Midrash Tanchuma, Balak 8). (See Rashi Genesis 22:3).