Judges 6:39-40

And Gideon said unto God, Let not thine anger be hot against me, and I will speak but this once: let me prove, I pray thee, but this once with the fleece; let it now be dry only upon the fleece, and upon all the ground let there be dew.

And God did so that night: for it was dry upon the fleece only, and there was dew on all the ground.