Judges 6:36-38

Then Gideon said to God, “You said you would help me save Israel. I will put some wool on the threshing floor. If there is dew only on the wool but all of the ground is dry, then I will know that you will use me to save Israel, as you said.” And that is just what happened. When Gideon got up early the next morning and squeezed the wool, he got a full bowl of water from it.