Isaiah 21:10

O my threshing, and the corn of my floor
Which may be understood either of the Babylonians, now threshed or punished by the Lord, and whom he had made use of as instruments for the punishment of others; or rather of the people of the Jews, whom the prophet calls "his", as being his countrymen, to whom he was affected, and with whom he sympathized; and besides, he speaks in the name of the Lord; or it is the Lord that speaks by him, calling the church of the Jews his floor, and the people his corn, which were dear and valuable to him, as choice grain, wheat, and other things; and therefore, though he threshed or afflicted them, it was for their good, to purge and cleanse them, and separate the chaff from them; and indeed it was on their account, and for their good, that all this was to be done to Babylon, before predicted; where they were, as corn under the threshing instrument, greatly oppressed and afflicted, but now should be delivered; for the confirmation of which it is added: that which I have heard of the Lord of hosts, the God of Israel,
have I declared unto you;
the preceding prophecy was not a dream of his, but a vision from the Lord of hosts; it was not devised by him, but told him by the Lord, and that for the good and comfort of the people of Israel, whose covenant God he was; and the prophet acted a faithful part, in delivering it just as he received it, which might be depended on.