John Calvin Commentary Isaiah 16:14

"But now Jehovah hath spoken, saying, Within three years, as the years of a hireling, the glory of Moab shall be brought into contempt, with all his great multitude; and the remnant shall be very small and of no account." — Isaiah 16:14 (ASV)

Three years. The time is fixed, not only for the sake of certainty, but also so that believers may not become faint through longer delay. He alludes to agreements among people, in which it is customary to fix the agreed-upon time, which the parties are not at liberty to violate.

This is especially the case in the labors of hired workers, from whom Scripture frequently draws a comparison in this respect: they earnestly long for the appointed day when they shall receive their reward, for they groan, as it were, under the burden and severely dislike their daily toils (Job 7:1–2, Job 14:6; Isaiah 21:16). In this way, the Lord says that he fixes a day for the Moabites, in which they shall not escape from the entire destruction of their power.

With all his multitude. He expressly mentions a multitude because their number was great, and because they boasted of it and thought that they were invincible. When he adds that the remnant shall be feeble, he means that there will be so great a change that they will have no resemblance to their former condition, for nothing will be left but a sad and shocking sight.