John Gill Commentary Numbers 23:8

"How shall I curse, whom God hath not cursed? And how shall I defy, whom Jehovah hath not defied?" — Numbers 23:8 (ASV)

How shall I curse whom God has not cursed ?
&c.] The sense is, that it was impossible for him to curse those that God did not curse himself, or would not have cursed by others; not but that he had a good will to it, to get Balak's money and honour, but he knew not how to accomplish it; yea, he saw it was in vain to attempt it, it was a thing that could not possibly be done: God does not, nor will he curse his spiritual Israel; they are blessed by him in Christ, and they shall be blessed; nor is it in the power of their enemies to curse them, or do them any harm:

The Targums of Jonathan and Jerusalem, instead of God and the Lord in this and the following clause, use the phase, ``the Word of the Lord;'' the essential Word, the Son of God, who is so far from cursing his people, that he has delivered them from the curses of the law, being made a curse for them, that the blessings of the everlasting covenant of grace might come upon them; and they are blessed of God in him, and for his sake, with all spiritual blessings:

or how shall I defy whom the Lord has not defied ?
which is the same thing in other words, only this last word is expressive of more contempt and indignation.