Judges 6:36-38

Then Gideon said to God, “If you are truly going to use me to rescue Israel as you promised, prove it to me in this way. I will put a wool fleece on the threshing floor tonight. If the fleece is wet with dew in the morning but the ground is dry, then I will know that you are going to help me rescue Israel as you promised.” And that is just what happened. When Gideon got up early the next morning, he squeezed the fleece and wrung out a whole bowlful of water.