Judges 6:36-38

And Gideon said unto God, If thou wilt save Israel by my hand, as thou hast spoken, behold, I will put a fleece of wool on the threshing-floor; if there be dew on the fleece only, and it be dry upon all the ground, then shall I know that thou wilt save Israel by my hand, as thou hast spoken. And it was so; for he rose up early on the morrow, and pressed the fleece together, and wrung the dew out of the fleece, a bowlful of water.