and build an altar to Yahweh your God on the top of this stronghold, in the orderly manner, and take the second bull, and offer a burnt offering with the wood of the Asherah which you shall cut down.
So here was Gideon hiding from the Midianites as he was threshing the wheat because if the Midianites had caught him they'd take the wheat. And so he was out by the winepress threshing wheat and here was an angel sitting under an oak tree.