“will wash.” The Hebrew is an example of the prophetic perfect idiom, speaking of a future event as if it was past. That “Judah” would wash his garments in “the blood of grapes” is a picture of abundance, but also almost certainly of the coming Messiah’s conquest of the earth. The Battle of Armageddon is referred to as the “winepress” because of all the blood that is spilled in that battle. There will be millions of people killed at that time, and their blood will splash onto Christ’s garments (Isa. 63:3; cp. Rev. 19:13). The Battle of Armageddon is also referred to as “the winepress” in Isaiah 63:2-3; Joel 3:13; Revelation 14:19-20 and 19:15 (see commentary on Rev. 19:15).
[For more on the prophetic perfect idiom, see commentary on Eph. 2:6.]