Amos 1:11

Thus saith the Lord for three transgressions of Edom
Or the Edomites, the posterity of Esau, whose name was Edom, so called from the red pottage he sold his birthright for to his brother Jacob: and for four, I will not turn away [the punishment] thereof;
(See Gill on Amos 1:3). Among these three or four transgressions, not only what follows is included, but their idolatry; for that the Edomites had their idols is certain, though what they were cannot be said; see ( 2 Chronicles 25:14 ) ; because he did pursue his brother with the sword:
not Esau his brother Jacob; for though he purposed in his heart to slay him, which obliged him to flee; and frightened him, upon his return, by meeting him with four hundred men; yet he never pursued him with the sword; but his posterity, the Edomites, not only would not suffer the Israelites their brethren to pass by their borders, but came out against them with a large army, ( Numbers 20:18-20 ) ; and in the times of Ahaz they came against Judah with the sword, and smote them, and carried away captives, ( 2 Chronicles 28:17 ) ; and were at the taking and destruction of Jerusalem, and assisted and encouraged in it, ( Psalms 137:7 ) ( Obadiah 1:11-14 ) ; though to these latter instances the prophet could have no respect, because they were after his time: and did cast off all pity;
bowels of compassion, natural affection, such as ought to be between brethren, even all humanity: or "corrupted", or "destroyed all pity" ^F23; showed none, but extinguished all sparks of it, as their behaviour to the Israelites showed, when upon their borders in the wilderness: and his anger did tear perpetually;
it was deeply rooted in them; it began in their first father Esau, on account of the blessing and birthright Jacob got from him; and it descended from father to son in all generations, and was vented in a most cruel manner, like the ravening of a lion, or any other beast of prey: and kept his wrath for ever;
reserved it in their breasts till they had an opportunity of showing it, as Esau their father proposed to do, ( Genesis 27:41 ) .