Jamieson, Fausset and Brown on Ezekiel 25:12

12. taking vengeance--literally, "revenging with revengement," that is, the most unrelenting vengeance. It was not simple hatred, but deep-brooding, implacable revenge. The grudge of Edom or Esau was originally for Jacob's robbing him of Isaac's blessing (Ge 25:23; 27:27-41). This purpose of revenge yielded to the extraordinary kindness of Jacob, through the blessing of Him with whom Jacob wrestled in prayer; but it was revived as an hereditary grudge in the posterity of Esau when they saw the younger branch rising to the pre-eminence which they thought of right belonged to themselves. More recently, for David's subjugation of Edom to Israel (2Sa 8:14). They therefore gave vent to their spite by joining the Chaldeans in destroying Jerusalem (Psa 137:7; La 4:22; Ob 10-14), and then intercepting and killing the fugitive Jews (Am 1:11) and occupying part of the Jewish land as far as Hebron.