Numbers 22:22-23

22But God was angry that he was going, 1and the angel of the Lord took his stand in the road as an adversary against him. Now he was riding on his donkey, and his two servants were with him.

23When the donkey saw the angel of the Lord standing in the road with his sword drawn in his hand, the donkey turned off from the road and went into the field; and Balaam struck the donkey to guide her back onto the road.