The book of Obadiah is the smallest book among the prophets containing only 21 verses in its entirety.
Obadiah was an earlier contemporary of the prophet Jeremiah and Jeremiah actually quotes him in his oracle against Edom in Chapter 49. Obadiah was obviously the specialist correspondent on Edom and he is appalled at that nation’s treachery when Jerusalem came under siege in the year 586 BC.
His anger is not the blind anger of the patriot who feels he’s been stabbed in the back, it is rather the visionary anger which is the response of true justice in the face of treachery.