Numbers 23:25

And Balak said unto Balaam, Neither curse them at all, nor bless them at all.

Balak said ... Neither curse them at all, nor bless them at all. Balak, being deeply mortified at what he must have considered the extraordinary treachery of Balaam, exclaimed, in the intensity of his disappointment, 'If thou wilt not curse, thou mayest at least refrain from blessing them.' Balak thought he had a constructive right to expect that at least Balaam would refrain uttering a blessing for Israel; because, as Hengstenberg justly remarks, by the very fact of the Mesopotamian seer having complied with the invitation to come to Moab for a definite purpose, he had laid himself under an obligation to do nothing contrary to the interest of the person who had summoned him.