Nombres 22:20

If [the men have come] to call you. If the invitation is for you, any you expect remuneration, then rise and go with them.

However. In spite of you, whatever I will say to you, you will do. Nevertheless, “Bil’am went.” He said, “perhaps I can convince him to agree.”

And the Word <mymr'> came from before the Lord unto Bileam in the night, and said to him, If these men come to call thee, arise, go with them; only, the word <ptgm'> that I will speak with thee, that shalt thou do.

[AND G-D CAME UNTO BALAAM AT NIGHT, AND SAID UNTO HIM]: ‘IF THE MEN ARE COME TO CALL THEE.’” ‘If the call be ‘for you’ [for your benefit] and you think you will receive a reward for it, then rise up, go with them. But [you should realize that even] against your will, the word which I speak unto thee, that shalt thou do’. And nevertheless Balaam went [as stated in the following verse], for he said: ‘Perhaps I may persuade Him to agree [that I should curse’].” This is Rashi’s language. “And G-d’s anger was kindled because he went. [This was because] Balaam realized that the matter was not pleasing in the sight of the Eternal, and [yet] he longed to go.” This too, is the Rabbi’s language.
And Rabbi Abraham ibn Ezra wrote: “The Gaon [Rav Saadia] said: If someone wishes to argue, saying: ‘Since He had told Balaam, Thou shalt not go with them, how is it that He told him [afterwards], Rise up, go with them?’ one may answer that G-d [indeed] did not want him to go with the first [emissaries], until more honorable princes than they would come. but with others, more honorable than they, you may go.” The reason for this may be that since Balaam, speaking against his intention and desire, was later on to confirm G-d’s love of Israel, it was fitting that this be done in the presence of more distinguished men than the former ones. But in my opinion [continues Ibn Ezra] there is no need for this [interpretation of the Gaon], for the meaning [of Rise up, go with them is not that this was a command, but] is like Send thou men [which is not a Divine command, but permission in the nature of a concession to Israel’s demand]. For G-d had said to Israel, Go up, take possession, but they did not believe [that they would conquer it], and said instead, Let us send men, Verse 22. — so Moses asked G-d [and He told him, Send thou men, meaning: ‘I do not command you, but if you wish to do so, send them’]. And this case [here too] is similar, for why did Balaam have to tell [Balak’s servants], tarry ye also here this night, that I may know what the Eternal will speak unto me more, [since G-d had already told him not to go with them]? It was because he harbored an evil intention in his heart [persisting in the hope that G-d would agree that he should go to Balak], and so G-d told him: ‘[You may] go with them, but be careful only to speak that which I will say to you.’ And the proof for …

אם לקרוא לך באו האנשים, if they only came in order to get your advice, as in Numbers 1,16 where such people who give advice are described as קרואי העדה, or in Samuel I 28,15 where a similar expression is used for advisors;

go ahead and accompany them in order to prevent them from sinning.

אם לקרוא לך באו האנשים, “if these men who have visited you came to invite you (in your professional capacity) etc.” I would not want you to accuse Me of having been instrumental in your forfeiting a substantial fee for your services.” However, I want you to say only words which have been approved by Me.” (You are not free to use your power of speech freely)