Numbers 22:20-23

²⁰And God came to Balaam by night, and said to him, If these men are come to call thee, rise and follow them; nevertheless the word which I shall speak to thee, it shalt thou do.

²¹And Balaam rose up in the morning, and saddled his ass, and went with the princes of Moab.

²²And God was very angry because he went; and the angel of the Lord rose up to withstand him. Now he had mounted his ass, and his two servants were with him.

²³And when the ass saw the angel of God standing opposite in the way, and his sword drawn in his hand, then the ass turned aside out of the way, and went into the field; and Balaam smote the ass with his staff to direct her in the way.