Obadiah 1:11

God cited one specific instance of Edom’s violence against her brother, but as I explained in the introduction, which instance is unclear. Edom’s treachery against Judah had taken place on a particular "day" in the past. Likewise God’s judgment would come on a particular "day" yet future (Obadiah 1:8). "Day" does not always refer to a period of 12 or 24 hours in the Bible. It sometimes refers to a longer period of time but one that is distinguishable as a period of time (e.g., Genesis 2:4). The Edomites’ sin was that they failed to help the Israelites in their hour of need (cf. Luke 10:31-32). Instead they stood aloof and watched joyfully as Israel’s invader plundered Jerusalem. Enemies passing though a city’s gate signified the loss of its self-rule. [Note: Niehaus, p. 529.] God considered the Edomites as guilty as Jerusalem’s invaders because the Edomites failed to help their brethren.

"In the sight of God, who looks not on the outward appearance but on the heart, there is little distinction in moral accountability between overt sin and an inner bias toward that sin that permits it to go unchecked (cf. Matthew 5:21-32)." [Note: Armerding, p. 348.]

". . . the Israelites are always commanded in the law to preserve a friendly and brotherly attitude towards Edom (Deut. ii. 4, 5); and in Deut. xxiii. 7 it is enjoined upon them not to abhor the Edomite, because he is their brother." [Note: Keil, 1:360.]