Or HaChaim on Numbers 23:25/אור החיים על במדבר כ״ג:כ״ה

1 גם קב לא חקבנו, "neither curse them, etc." Both the word גם, "also," and the repetition of the verb קב present a difficulty in this verse. Inasmuch as Bileam had told Balak to get up and listen carefully (23,18), Balak interpreted this as a hint that Bileam actually wanted to curse the Israelites but that G'd had thwarted him, as we explained. In view of what had just occurred he said גם to express his dismay that not only had Bileam not cursed the people but had even blessed them. He referred to two possibilities of cursing when he repeated the word. Alas, Bileam had not only not named Israel as the object of a curse but had not even uttered a curse without specifically naming the victim. We may infer from Balak's words that Bileam had been looking for a way of uttering a curse without at the same time incurring punishment at the hands of G'd. He wanted to utter a curse indiscriminately, naming the victim only in his heart. This is the reason that G'd had to prevent him from even uttering a curse without naming anybody.

2גם ברך, "also blessing, etc." In view of the fact that Bileam had explained to Balak that the blessings he had uttered were forced upon him, Balak now demurs saying that if he could not curse them at least he was not obligated to bless them. Balak was under the impression that G'd twisted Bileam's mouth so that a blessing came out only because Bileam had tried to utter a curse first. He repeated the verb i.e. לא תברכנו, do not bless them, to protest even a blessing which Bileam did not mean honestly.