Charles Ellicott Commentary Numbers 24:13

"If Balak would give me his house full of silver and gold, I cannot go beyond the word of Jehovah, to do either good or bad of mine own mind; what Jehovah speaketh, that will I speak?" — Numbers 24:13 (ASV)

I cannot go beyond the commandment of the Lord. —Hebrew, the mouth of the Lord: the same expression which is used in Numbers 22:18, where the Authorised Version has “the word of the Lord.”