Numbers 22:18-22

And Balaam answered and said unto the servants of Balak, If Balak would give me his house full of silver and gold, I cannot go beyond the word of the LORD my God, to do less or more.

Now therefore, I pray you, tarry ye also here this night, that I may know what the LORD will say unto me more.

And God came unto Balaam at night, and said unto him, If the men come to call thee, rise up, and go with them; but yet the word which I shall say unto thee, that shalt thou do.

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

And God’s anger was kindled because he went: and the angel of the LORD stood in the way for an adversary against him. Now he was riding upon his ass, and his two servants were with him.