to beat with a hand-held stick so that what is wanted falls loose: olives off a tree, grain or seed out of the stalk
This is the verb of the stick. A worker takes a pole or a rod in hand and strikes: the branches of an olive tree, so the ripe fruit drops onto the ground or onto spread cloths, or a heap of cut stalks, so the kernels come free. All five places the word appears are farming scenes, and in every one the scale is small and personal: one person, one stick, one day's worth of harvest.
That smallness is the reason a writer reached for this word rather than the ordinary word for threshing (דּוּשׁ), which pictures oxen dragging a heavy studded sledge back and forth across an open floor. Isaiah 28:27 puts the two side by side to make exactly that contrast: delicate seed is not crushed under a sledge or run over by a cart wheel, it is tapped out with a rod. The same choice is telling in Judges 6:11, where Gideon is found beating out wheat inside a winepress: a stick is quiet and a rock-cut pit is hidden, which is what a man does when raiders are in the land. In Ruth 2:17 it is the modest, exact word for what one gleaner does with what she has picked up by hand all day.
Isaiah then takes that humble motion and makes it a picture of God. He will beat out his scattered people across the whole stretch of country from the Euphrates to the border of Egypt, and they will be gathered up one at a time. The force of the image rests entirely on the instrument: a sledge would pulverize, while a stick shakes loose what is wanted and leaves it whole.
Nuances
Whether Isaiah 27:12 pictures olives being beaten from a tree, grain being beaten out of the stalk, or both at once, given that the verse names no object for the verb.
- contestedGrain being beaten out, matching the threshing scenes of Judges 6:11 and Ruth 2:17, with possible wordplay on a noun that can mean either a flowing channel or an ear of grain.; Hans Wildberger, Isaiah 28-39 (Continental Commentary, ET 1997), 605-12; Joseph Blenkinsopp, Isaiah 1-39 (Anchor Bible 19), 377-78; John D. W. Watts, Isaiah 1-33 (WBC 24), 419-20
- contestedOlives being knocked from the branches, since the following verb is the ordinary word for gleaning and the gathering is individuated "one by one", echoing Isaiah 17:6 and 24:13.; J. Alec Motyer, The Prophecy of Isaiah (IVP, 1993), 226-27; BDB, s.v. חבט, 286 (citing Cheyne, Dillmann, and Duhm)
- contestedThe ambiguity is deliberate, so that both harvests are evoked at once; on either reading the point is a careful, individuated ingathering.; Brevard S. Childs, Isaiah (OTL, 2001), 199-201; Willem A. M. Beuken, Isaiah II (Historical Commentary on the Old Testament)