Numbers 22:33-35

33Three times the donkey saw me and turned back. If it had not done that, I would have killed you. But I would not have killed your donkey.’

34Then Balaam said to the angel of the Lord, ‘I have done a wrong thing. I did not realize that you were standing in the road to stop me. If you do not want me to continue, I will return to my home.’

35But the angel of the Lord said to Balaam, ‘Go with the men. But you must say only the words that I will tell you.’ So Balaam went with Balak's officers.