Judges 6:37 Behold, I will put a fleece of wool on the floor; and if the dew be on the fleece only, and it be dry on all the earth beside, then shall I know that thou wilt save Israel by thine hand, as thou hast said.
Gideon wanted to believe God, but in human unbelief he could not be sure. Therefore, he challenged God for proof of His word and promise: he put a fleece on the floor, saying make the fleece wet and the earth around it dry. And God did so. Just as he requested. But he did it a second time, only this time he asked to make the fleece dry and the earth wet with dew. And God did so.
There is open debate on the question whether Gideon should have challenged the Lord in this manner. I think not: lingering doubt caused him to put out a fleece. The Lord had already appeared to him and told him what He would do. It should be enough for us to simply believe His promise and do what He says. But whether Gideon was right or wrong, God answered his further request for proof.
The Lord understands doubt and unbelief, and loves us anyway. Although Jesus rebuked Thomas’ doubt, He let him touch His resurrected body anyway. Such is His Love. But He did say, “Blessed are those who have not seen, and yet have believed.” We have the Word of God and it is enough. Faith sees. Doubt wants proof. Jesus sends the Spirit to convince through Word and Sacrament. We don’t need to see a sign, though Jesus does grant them.