Albert Barnes Commentary Obadiah 1:5

"If thieves came to thee, if robbers by night (how art thou cut off!), would they not steal [only] till they had enough? if grape-gatherers came to thee, would they not leave some gleaning grapes?" — Obadiah 1:5 (ASV)

If thieves came to you - The prophet describes their future punishment, by contrast with that which, as a marauding people, they well knew. Thieves and robbers spoil only for their petty end. They take what comes to hand; what they can, they carry off. Shortness of time, difficulty of transport, and the necessity of providing for a retreat limit their plunder. When they have gorged themselves, they depart.

Their plunder is limited. The grape-gatherer leaves gleanings. God promises to His own people, under the same image, that they should have a remnant left (Isaiah 17:6; Isaiah 24:13): Gleaning grapes shall be left in it. It shall be, as gleaning grapes, when the vintage is done. The prophet anticipates the contrast by a burst of sympathy.

In the name of God, he mourns over the destruction which he foretells. He laments over the destruction, even of the deadly enemy of his people. How are you destroyed! So the men of God are accustomed to express their amazement at the greatness of the destruction of the ungodly (Psalms 73:19). How are they brought into desolation as in a moment! (Isaiah 14:4, 14:12). How has the oppressor ceased! How are you fallen from heaven, O Lucifer, son of the morning! (Jeremiah 50:23). How is the hammer of the whole earth cut asunder and broken! How is Babylon become a desolation among the nations! (Jeremiah 51:41). How is Sheshach taken! How is the praise of the whole earth surprised!