Numbers 22:18-20; Numbers 22:35

18 Balaam replied to the servants of Balak, "Though Balak were to give me his house full of silver and gold, I could not do anything, either small or great, contrary to the command of the LORD my God.

19 "Now please, you also stay here tonight, and I will find out what else the LORD will speak to me."

20 God came to Balaam at night and said to him, "If the men have come to call you, rise up and go with them; but only the word which I speak to you shall you do."

35 But the angel of the LORD said to Balaam, "Go with the men, but you shall speak only the word which I tell you." So Balaam went along with the leaders of Balak.