John Calvin Commentary Isaiah 17:5

"And it shall be as when the harvestman gathereth the standing grain, and his arm reapeth the ears; yea, it shall be as when one gleaneth ears in the valley of Rephaim." — Isaiah 17:5 (ASV)

And it shall be as when the harvester gathers the corn. He shows by a comparison how great the desolation will be. “As the reapers,” he says, “gather the corn in armfuls, so this multitude, though large and extended, will be mowed down by the enemies.” Now, to ensure no remnant is left, he adds that at the conclusion of the harvest the ears will be gleaned, as if to say that when the multitude has been destroyed and the country laid bare like a reaped field, not even the shaken and scattered ears will be left.

Besides, he uses the metaphor of a harvest because the people, trusting in their great numbers, feared nothing; but just as reapers are not terrified by the large quantity of corn, so he declares that their vast numbers will not prevent God from utterly destroying them. This may also refer to the Assyrians, but the meaning will be the same, for they were God’s servants in executing this vengeance.

We do not need to spend much time explaining the word gather, for it simply means that the slaughter will resemble a harvest, which concludes with the gleaning of the ears. When the ten tribes had been carried away, the Assyrians, having learned that they were planning a revolution, destroyed them also (2 Kings 17:4). He especially mentions the valley of Rephaim, because its fertility was well known to the Israelites.