Midrasch zu Bamidbar 22:36

16 (Numb. 22:36) “When Balak heard that Balaam had come.” [These words] teach that he sent messengers unto [Balak] to send him tidings. (Ibid., cont.) “He went out to meet him unto the city of Moab,” [i.e.,] unto their metropolis.²³Gk. and Lat.: metropolis. What was [Balak's] reason for preceding him to the borders? He said to him, “These are borders which have been fixed from the days of Noah, so that a nation would not enter the territory of its neighbor. These [people] are coming to uproot them.” Then he showed him how they had broken through and crossed the border of Sihon and Og, as though lodging a complaint against them. (Numb. 22:37) “Then Balak said unto Balaam, ‘Did I not truly send unto you to summon you; [why did you not come unto me;] am I really unable to honor you’”: He prophesied that his end would be to go in disgrace. Then did Balaam also answer him like the [truth of the] matter (in Numb. 22:38), “So Balaam said unto Balak, ‘See, I have come unto you now, but am I really able to say anything at all?’” For I do not have authority to say what I want.