The reasons for the judgment upon edom predicted by were probably related to edom's assistance to the philistines and arabians in their raid upon jehoram and jerusalem. obadiah isaiah hosea

I believe the answer is: Obadiah.
In obadiah, it's written that Edom has been the enemy of Israel and has been constantly caused many bad situation for Israel.
On top of that, the God also has written eights warning to Edom that all have been ignored, which contribute to the God's anger toward them.