And God’s anger burned because he was going, and an angel of Hashem stationed himself in the way as an adversary to him; and he was riding on his donkey, and his two lads were with him.
Bamidbar Rabbah 20:14 — why anger after permission had been given.
Sefaria — Bamidbar Rabbah 20:14
English: “And God’s anger burned because he was going.” But had permission not been given him? Rather, because he went with joy.
Resolution of apparent contradiction between permission and anger.
Permission to go did not license eagerness to harm Israel — joy in the mission is what kindled the anger.