And the ass saw the angel of the LORD standing in the way, and his sword drawn in his hand: and the ass turned aside out of the way, and went into the field: and Balaam smote the ass, to turn her into the way.
The donkey saw an angel of God standing with a sword, so it swerved from the path and went into a field. Balaam hit the donkey to try to make it go back on track.