What does Obadiah 1:5 mean?

This verse provides additional details of the coming judgment on Edom. Even though Edom and Israel were descended from brothers, Edom had long persecuted Israel. When this prophecy was spoken, Edom was wealthy and well-defended. Israel, on the other hand, had just been defeated—for the third time in a few decades—by foreign armies. Rather than helping their "brother" nation, the Edomites actually helped the invaders. As a result, this verse is both an accusation and a prediction.

A typical thief will only steal what they want and then leave. A typical harvester will take good grapes, but leave bits and pieces behind for the poor. A thief who steals everything, or who burns down the house, is acting out of spite. The same would be true of a harvester who purposefully leaves nothing for the poor to collect. When a foreign nation attacked Israel, Edom joined in the looting. Even though they were already wealthy, and Israel was already destitute, the Edomites robbed the Jews.

At the same time, this verse is a prediction of what will happen to Edom. A common theme of Old Testament prophecy is the idea of reaping what is sown. That is, the crimes of a nation are often exactly what they will suffer when judgment comes. In the case of Edom, their judgment will include being completely and totally ruined. Thieves might steal, but Edom would see everything they had taken away. Malachi 1:3–4, written some time later, describes Edom's cities as abandoned.