This is set after one of the times Babylon came and pillaged Israel, but there’s no way to tell which time. There’s just one chapter to this book, one vision of the prophet Obadiah.
This is entirely about Edom standing by while Israel gets destroyed and taken away as captives. God is angry with Edom because they were Israel’s brother, so to speak, and should have defended them. Instead they stood by and did nothing.
This is another one of those places where “as” shows up and is rather disconcerting.
15For the day of the LORD is near upon all the nations.
As you have done, it shall be done to you;
your deeds shall return on your own head.
There’s no questioning this instance of it, either. The sentiment is to look out for what you do to people, the consequences is that it be done to you. I suppose that’s part of where we get the old adage, “do unto other as you would have done unto you.” God seems to be a big believer in it. Perhaps He simply sees it as an adequate consequence of our own behaviors. Well, Edom is getting it here.