Numbers 22
20 Ref And that night God came to Balaam and said to him, If these men have come for you, go with them: but do only what I say to you.
21 Ref So in the morning Balaam got up and, making his ass ready, went with the chiefs of Moab.
22 Ref But God was moved to wrath because he went: and the angel of the Lord took up a position in the road to keep him from his purpose. Now he was seated on his ass, and his two servants were with him.