They called the altar Ed That is, a witness; a witness of the relation they stood in to God and Israel, and of their concurrence with the other tribes in the common faith, that Jehovah he is God. It was a witness to posterity of their care to transmit their religion pure and entire; and it would be a witness against them, if ever they should turn from following the Lord.
Related Commentaries of Joshua 22:34
Joshua 22:34
34 And the children of Reuben and the children of Gad called the altar Ed: for it shall be a witness between us that the LORD is God.