Edom was another betrayer (see Amos 1:9; Genesis 36; see also Genesis 25:23–30; 27:39–40).
The word brother refers to Edom’s close family relationship with Israel, since both peoples came from Isaac’s sons (see Genesis 25:25–30). The word brothers can also describe groups that are bound together by a treaty (see Amos 1:9).
In this passage, Edom’s guilt lies in its ongoing hostility toward Israel and Judah. Edom repeatedly attacked Israel’s borders and took advantage of times of weakness by raiding and stealing (Jeremiah 49:7–22; Obadiah 1:1–9).