Moses charged the priests with the care and keeping of the law he had written (vv. 25-26), perhaps the whole Book of Deuteronomy.333It was normal for priests to bear this responsibility in the ancient Near East.334They kept this document beside, not in, the ark (v. 26; cf. 2 Kings 22:8). Only the Ten Commandments were in the ark (Exod. 25:16; cf. Exod. 16:33-34; Num. 17:10-11). The Levites who carried the ark were Kohathites. The song (vv. 15-16) and the scroll were two witnesses to the people's obedience and disobedience. Moses also warned the priests of Israel's future apostasy as God had revealed this to him (vv. 27-29). It was important that these spiritual leaders be ready for what was coming.
"What appears to be in view is a miniature preenactment of the ceremony that the whole nation was to engage in at Ebal and Gerizim once Canaan had been overcome and occupied (cf. 27:1-14)."335