Commentaire sur La Genèse 36:33

יובב בן זרח מבצרה JOBAB, THE SON OF ZERAH OF BOZRAH — Bozrah was one of the Moabite cities, as it is said (Jeremiah 48:24 which chapter is a prophecy against Moab), “[Judgment is come upon…] and upon Keriath and upon Bozrah etc.” Because it produced a king for Edom it is to be smitten together with them (the Edomites), as it is said (Isaiah 34:6) “For the Lord hath a slaughtering in Bozrah, [and a great slaughter in the Land of Edom]’ (Genesis Rabbah 83:3).

Because it provided a king for Edom it is destined to be smitten together with them... Rashi is answering the question: Why does the verse identify Yovav by his father, if it [also] identifies him by his place? [The place alone should suffice,] as with “Samlah of Masriekah” (v. 36), etc. Rashi answers: Yovav was not well known by his place. Scripture mentions his place only in order to teach, “It is destined to be smitten...” (R. Hendel)