John Gill Commentary Numbers 23:5

"And Jehovah put a word in Balaam`s mouth, and said, Return unto Balak, and thus thou shalt speak." — Numbers 23:5 (ASV)

And the Lord put a word in Balaam's mouth
&c.] Not grace into his heart, nor the fear of God within him, but suggested to him what to say; impressed it strongly on him, that he could not forget it, and with such power and weight, that he was obliged to deliver it:

and said, return unto Balak, and thus shall you speak ;
that is, unto him, and what is expressed in (Numbers 22:7–10) .