The expression “to put out a fleece” is an old English expression meaning to ask God to do something to show that a thing to be His will. The expression comes from Gideon's story. Gideon, our reluctant hero, wants to make sure he is doing the right thing, so he asks the Lord to make a fleece wet one night and dry the next to ensure he is doing God’s will. Many ask how this is reconciled with passages that command us not to put the Lord to the test?
