Numbers 22:20-23

²⁰And God came unto Balaam at night, and said unto him: 'If the men are come to call thee, rise up, go with them; but only the word which I speak unto thee, that shalt thou do.'

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

²²And God's anger was kindled because he went; and the angel of the LORD placed himself in the way for an adversary against him. — Now he was riding upon his ass, and his two servants were with him. —

²³And the ass saw the angel of the LORD standing in the way, with 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.