Albert Barnes Commentary Numbers 23:20

"Behold, I have received [commandment] to bless: And he hath blessed, and I cannot reverse it." — Numbers 23:20 (ASV)

I have received commandment to bless — literally, “I have received to bless.” The reason for his blessing lay in the augury which he acknowledged, and in the divine overruling impulse which he could not resist, not in any “commandment” in words.