Albert Barnes Commentary Judges 6:26

"and build an altar unto Jehovah thy God upon the top of this stronghold, in the orderly manner, and take the second bullock, and offer a burnt-offering with the wood of the Asherah which thou shalt cut down." — Judges 6:26 (ASV)

In the ordered place - See the margin. “Build an altar, etc., with the materials,” the wood laid in order , that is, what he would find ready to hand in the altar of Baal which he was to throw down.

The wood of the grove - “The (blocks of) wood of the idol,” that is, the image of Astarte. The command from God Himself to build an altar and sacrifice upon it is analogous to Elijah’s sacrifice (1 Kings 18), and was doubtless caused by the extraordinary circumstance of the defection of the Israelites from the worship of the true God. Possibly, too, the Midianite invasion had made the worship at Shiloh impossible at this time.