my threshing - that is, my people (the Jews) trodden down by Babylon.
corn of my floor - Hebrew, “my son of the floor,” that is, my people, treated as corn laid on the floor for threshing; implying, too, that by affliction, a remnant (grain) would be separated from the ungodly (chaff) [Maurer]. Horsley translates, “O thou object of my unremitting prophetic pains.” See Isa 28:27, Isa 28:28. Some, from Jer 51:33, make Babylon the object of the threshing; but Isaiah is plainly addressing his countrymen, as the next words show, not the Babylonians.