And I will fill his mountains with his slain men,.... Not only Mount Seir, but all the rest of the mountains, in Idumea; where they shall flee for refuge, and the enemy shall pursue them, and slay them; and where their carcasses will fall in such numbers, as to cover the mountains with them; compare with this Revelation 19:18:
in thy hills, and in thy valleys, and in all thy rivers, shall they fall that are slain with the sword: expressive of the greatness and universality of the slaughter, that it should be a general one everywhere; hence rivers and fountains are said to become blood, through the number of the slain, Revelation 16:3.