Numbers 22:20-23

²⁰That night God appeared to Balaam again and said to him, “These men have come to request that you go back with them, so you may go with them, but do only what I tell you to do!”

²¹So the next morning, Balaam put a saddle on his donkey and he departed with two of his servants along with the men from Moab.

²²Even though God had given Balaam permission to go, he was still angry. So he sent one of his angels to Balaam. This angel stood in the road to block Balaam's path. As Balaam and the two servants were riding on their donkeys,

²³Balaam's donkey saw the angel. The angel was standing in the road and was holding a sword in his hand, but Balaam did not see him. Balaam's donkey turned off the road into a field. So Balaam struck the donkey and forced it to go back onto the road.