37 behold, I will put a fleece of wool on the threshing floor; if there be dew on the fleece only, and it be dry on all the ground, then shall I know that you will save Israel by my hand, as you have spoken."
*Minor differences ignored. Grouped by changes, with first version listed as example.
The threshing floors were and still are under the open air, and usually circular. The second sign Judges 6:40, would be more convincing than the former, because it is the nature of fleeces to attract and retain moisture.
Behold, I will put a fleece of wool on the floor,.... On the floor where he was threshing, where the angel first appeared to him, and which lay exposed to the open air, so that the dew might easily fall upon it:
and if the dew be on the fleece only; the dew that falls from heaven in the night, when he proposed it should lie on the floor till morning:
and it be dry upon all the earth beside; meaning not upon all the world, nor even upon all the land of Israel, but upon all the floor about the fleece: then shall I know that thou wilt save Israel by my hand, as thou hast said; for the dew being a token of divine favour, see Hosea 14:5 it would show that Gideon would partake of it, while his enemies would be dry and desolate, and ruin and destruction would be their portion.
On all the earth - That is, upon all that spot of ground which encompasses the fleece.
*More commentary available at chapter level.