Commentaire sur Les Nombres 20:14

אחיך ישראל THY BROTHER ISRAEL — What reason had he to mention here their brotherhood? But in effect he said to him: We are brothers, sons of Abraham to whom it was said, (Genesis 15:13) “know for a surety that thy seed shall be a stranger [in a land not theirs]”, and upon both of us, being of Abraham’s seed, was the duty of paying that debt (Midrash Tanchuma, Chukat 12).

AND MOSES SENT MESSENGERS FROM KADESH UNTO THE KING OF EDOM. Scripture did not mention the king’s name, because there was no necessity to do so. It did, however, mention Sihon and Og, the kings of the Amorites, by name, because they were famous for their strength, and they had a name among¹⁹⁵See II Samuel 23:18. the nations; [therefore it stresses] that we should give thanks to Him, blessed be He, for having dealt wondrously with us, as it is said, To Him that smote great kings; for His mercy endureth for ever … Sihon king of the Amorites; for His mercy endureth for ever. And Og king of Bashan; for His mercy endureth for ever.¹⁹⁶Psalms 136:17-20. And it is customary for Scripture to mention the names of the great kings whose lands we inherited, just as it mentioned in [the Book of] Joshua the five kings of the Amorites:¹⁹⁷Joshua 10:5. Adoni-zedek king of Jerusalem, and Hoham king of Hebron, and Piram king of Jarmuth, and Japhia king of Lachish, and Debir king of Eglon.¹⁹⁸Ibid., Verse 3. [It mentioned also] Jabin king of Hazor,¹⁹⁹Ibid., 11:1. but the rest of the kings it mentioned only by number,²⁰⁰Ibid., 12:9-24. not by name [because they were not famous for their strength]. Scripture states [here], And ‘Edom’ said unto him²⁰¹Verse 18. ‘Thou shalt not pass through me, lest I come out with the sword against thee.’ [and it does not say: “and ‘the king’ of Edom said”], because the whole people agreed with their ruler in his refusal [to allow the Israelites to pass through their land].

אחיך ישראל, אתה ידעת "your brother Israel; you are aware, etc." The reason that Moses underlined the brotherly connection between Edom and Israel was to remind Edom that the discomfort of travel Israel experienced now was not due to recent events but to their respective ancestor and that he considered both Israel and Edom as being involved in this equally. Abraham's descendants were supposed to experience exile according to Genesis 15. However, only the descendants of one of Isaac's sons had paid the price by being enslaved in Egypt. Esau and his descendants had not experienced any of that suffering. The least the Edomites could do now was to display some degree of brotherliness by allowing the Jewish people passage to their own heritage. Compare Bereshit Rabbah 82, on Genesis 36,8 where it is explained that the reason Esau emigrated was that he did not want to pay the debt Abraham had contracted for at the covenant between the pieces.