I believe that was Chapter 6 of Reading the Bible for All It's Worth.
And the book of judges, of course.
19And Gideon went in, and made ready a kid, and unleavened cakes of an ephah of flour: the flesh he put in a basket, and he put the broth in a pot, and brought
it out unto him under the oak, and presented
it.
20And the angel of God said unto him, Take the flesh and the unleavened cakes, and lay
them upon this rock, and pour out the broth. And he did so.
21Then the angel of the LORD put forth the end of the staff that
was in his hand, and touched the flesh and the unleavened cakes; and there rose up fire out of the rock, and consumed the flesh and the unleavened cakes. Then the angel of the LORD departed out of his sight.
22And when Gideon perceived that he
was an angel of the LORD, Gideon said, Alas, O Lord GOD! for because I have seen an angel of the LORD face to face.
23And the LORD said unto him, Peace
be unto thee; fear not: thou shalt not die
It seems pretty obvious using our own sense of human reasoning that Gideon should not have needed additional miraculous signs after this event. And as you read the rest of the chapter there is a momentum of faith actions performed on Gideon's part that brings him to the brink of the battle, but then...
36And Gideon said unto God, If thou wilt save Israel by mine hand, as thou hast said,
37Behold, I will put a fleece of wool in the floor;
and if the dew be on the fleece only, and
it be dry upon all the earth
beside, then shall I know that thou wilt save Israel by mine hand, as thou hast said.
38And it was so: for he rose up early on the morrow, and thrust the fleece together, and wringed the dew out of the fleece, a bowl full of water.
39And 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.
40And God did so that night: for it was dry upon the fleece only, and there was dew on all the ground.
So without the text saying it we get the natural idea that he is nervous... needing confirmation. For whatever reason he is second guessing everything he has experienced prior to this. He needs another sign and "then he shall know" so that does seem like he does not yet know and I would call that doubt. I think there is every reason to call this fleece request an act of doubt.
I would agree that God is granting his request in spite of his second guessing what God had already told him. An act of grace on Gods part but you naturally feel a little uncomfortable when you read it. You want to tell Gideon, "Dude! God already had an angel visit you and miraculously burn up your offering why are you asking for more?" But God in his grace does it anyway. That is an awesome thing and we sort of sigh in relief that God did not make one of his hands leprous or strike him dumb and unable to speak until the battle was over or something like that.
Do we really see any precedence here for making this a method for knowing Gods will on a matter? After all God had already told Gideon what to do. If Gideon had never asked for this fleece we could have told him "Gideon.. you know what to do, just do it". So nothing new was added to Gideon concerning what God wanted him to do by going through this fleece test. Do we have the authority to take this story and use it to support the idea that we should ask God to make something happen for us to confirm what he has already told us is what we should do?
Does this story tell us that this is Gods method for how to get confirmation from God? Why or Why not?
And if it is, then do we have the authority to change the method. Should we ask God a question and tell him if the answer is yes make my coat dry but the grass around it wet. And then check it in the morning? And if it is dry, ask again for it to be wet this time. Is that what we should do? That is what he did and we are claiming this as our scriptural authority.