11. Edom . . . did pursue his brother-- (Isa 34:5). The chief aggravation to Edom's violence against Israel was that they both came from the same parents, Isaac and Rebekah (compare Ge 25:24-26; De 23:7, 8; Ob 10, 12; Mal 1:2).
      cast off all pity--literally, "destroy compassions," that is, did suppress all the natural feeling of pity for a brother in distress.
      his wrath for ever--As Esau kept up his grudge against Jacob, for having twice supplanted him, namely, as to the birthright and the blessing (Ge 27:41), so Esau's posterity against Israel (Nu 20:14, 21). Edom first showed his spite in not letting Israel pass through his borders when coming from the wilderness, but threatening to "come out against him with the sword"; next, when the Syrians attacked Jerusalem under Ahaz (compare 2Ch 28:17, with 2Ki 16:5); next, when Nebuchadnezzar assailed Jerusalem (Ps 137:7, 8). In each case Edom chose the day of Israel's calamity for venting his grudge. This is the point of Edom's guilt dwelt on in Ob 10-13. God punishes the children, not for the sin of their fathers, but for their own filling up the measure of their fathers' guilt, as children generally follow in the steps of, and even exceed, their fathers' guilt (compare Ex 20:5).

JFB.