וַיֹּ֕אמֶר קְרָ֥א שְׁמ֖וֹ לֹ֣א עַמִּ֑י כִּ֤י אַתֶּם֙ לֹ֣א עַמִּ֔י וְאָנֹכִ֖י לֹֽא־אֶהְיֶ֥ה לָכֶֽם׃ (ס)
און ער האָט געזאָגט: רוף זײַן נאָמען לא-עמי, וואָרום איר זײַט ניט מײַן פֿאָלק, און איך בין ניט אײַערער.
Rabbeinu Bahya
A Midrashic approach based on Tanchuma Massey 7: Bileam who foresaw that there would arise a man in the future who would proclaim himself as god (the founder of Christianity) exclaimed how can it be that a mere mortal so deceives his peers? He predicted that this individual would have to regret what he said seeing he would not be able to demonstrate the truth of it [seeing he was executed. Who can execute a god? Even men who had not claimed to be god were saved from fiery furnaces, etc. Should the god not be able to take care of himself if he really were god? Ed.].
However, of G’d it is to be expected that when He promises something good that He will invariably fulfill this promise, i.e. לא איש אל ויכזב, “G’d is not like man who promises without delivering.” On the other hand, when G’d threatens something harmful, such a threat need not come true (as it is merely a warning for the intended victim to change his ways). This is expressed here in the words ההוא אמר ולא יעשה, “He may say something (and is not bound by it) to carry it out.” Example: G’d told Avraham (Genesis 15,5) to count the stars and to see if he could count them, meaning that his descendants would be equally numerous. The promise was fulfilled as Moses told the people in Deut. 1,10: “here you are today as numerous as the stars in heaven” [no one challenged that statement. Ed.]. This was an illustration of the words: “G’d is not man that He deceives.” On the other hand, although we find the prophet Hoseah 1,9 telling the people (in the name of G’d) “you are not My people,” in Hoseah 2,25 the same prophet assures the people “I will say to Lo-Ammi,“ [the people who had previously been told that they were not G’d’s people. Ed.] “you are My people.” This is an illustration of what Bileam meant when he said about G’d: “He may say, but need not do.” This is the way Tanchuma understands the verse.
However, of G’d it is to be expected that when He promises something good that He will invariably fulfill this promise, i.e. לא איש אל ויכזב, “G’d is not like man who promises without delivering.” On the other hand, when G’d threatens something harmful, such a threat need not come true (as it is merely a warning for the intended victim to change his ways). This is expressed here in the words ההוא אמר ולא יעשה, “He may say something (and is not bound by it) to carry it out.” Example: G’d told Avraham (Genesis 15,5) to count the stars and to see if he could count them, meaning that his descendants would be equally numerous. The promise was fulfilled as Moses told the people in Deut. 1,10: “here you are today as numerous as the stars in heaven” [no one challenged that statement. Ed.]. This was an illustration of the words: “G’d is not man that He deceives.” On the other hand, although we find the prophet Hoseah 1,9 telling the people (in the name of G’d) “you are not My people,” in Hoseah 2,25 the same prophet assures the people “I will say to Lo-Ammi,“ [the people who had previously been told that they were not G’d’s people. Ed.] “you are My people.” This is an illustration of what Bileam meant when he said about G’d: “He may say, but need not do.” This is the way Tanchuma understands the verse.