This is what the LORD says: “For three transgressions of Edom, even four, I will not revoke My judgment, because he pursued his brother with the sword and stifled all compassion; his anger raged continually, and his fury flamed incessantly.
The Prophet now passes to the Idumeans themselves. He had denounced ruin on the uncircumcised nations who delivered up the Jews into their hands: but they deserved a much heavier punishment, because their crime was much more atrocious. The Idumeans derived their origin, as it is well known, from their common father Isaac and bore the same symbol of God’s covenant, for they were circumcised.
What the Lord says here may be explained by what he says Jer 12:14, Thus said the Lord, against all my evil neighbours that touch the inheritance of my people Israel, Behold, I will pluck them out. Damascus was a near neighbour to Israel on the north, Tyre and Gaza on the west, Edom on the south, Ammon and (in the next chapter) Moab on...
Commenting on Amos 1:3-15
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 Amo 1:3.