To cut short — whether crops at harvest or days of life. The harvest image permeates both agricultural law (leave gleanings for the poor) and eschatological judgment ('the harvest is ripe').
Israel's agricultural calendar centered on harvest. The laws of gleaning (Lev 19:9-10) showed that qatsar was not purely economic but ethical. NT harvest imagery (Matt 13, Rev 14) builds on this.
The harvest as divine judgment is developed through Hosea and Joel into a major eschatological image. Jesus' parables of the harvest (tares, dragnet) and Revelation 14's harvest angel all echo qatsar.