Jamieson, Fausset and Brown on Joshua 8:32

32. he wrote there upon the stones a copy of the law of Moses--(See on De 27:2, 3, 5); that is, the blessings and curses of the law. Some think that the stones which contained this inscription were the stones of the altar: but this verse seems rather to indicate that a number of stone pillars were erected alongside of the altar, and on which, after they were plastered, this duplicate of the law was inscribed.