C. F. Keil and Franz Delitzsch on Joshua 22:16

Jos 22:16

Assuming at the outset that the altar was intended for a second place of sacrifice in opposition to the command of God, the delegates, with Phinehas no doubt as their speaker, began by reproaching them for falling away from the Lord. “What faithlessness is this (מעל: see at Lev 5:15) that ye have committed against the God of Israel, to turn away this day from Jehovah, in that ye have builded you an altar, that ye might rebel this day against Jehovah?” מרד (to rebel) is stronger than מעל.