Or HaChaim on Numbers 22:16/אור החיים על במדבר כ״ב:ט״ז

1 אל נא תמנע, "please do not be prevented, etc." Inasmuch as the first set of delegates had come to the conclusion that Bileam had declined their invitation for reasons of his own, they expressed the hope that his desire for the appropriate honour had now been satisfied. There was therefore no further obstacle that could prevent him from acceding to their request. Bileam, who was not aware that the first set of emissaries had suspected him of merely inventing G'd's prohibition interpreted the words of the new delegates to mean that he should ignore what G'd had told him and should come against G'd's will. This is why he made a point of saying that his previous refusal had nothing to do with the size of his fee or his personal honour, but that he was unable to contravene G'd's instructions. He explained that he was not free to exercise his free will in this matter.