On that day Moses commanded the people:
11. And Moses charged the people the same day. In order that both the promises and threats might have more efficacy in affecting the minds of all, God enjoined not only that they should be proclaimed in a solemn rite, but also that they should be approved by the people in a loud voice, and sealed, as it were, by their consent.
When the law was written, to be seen and read by all men, the sanctions of it were to be published, which, to complete the solemnity of their covenanting with God, they were deliberately to declare their approbation of. This they were before directed to do (Deu 11:29, Deu 11:30), and therefore the appointment here begins somewhat abruptly, Deu 27:12.
Commenting on Deuteronomy 27:11-26
And Moses charged the people the same,.... That he gave the above orders to set up stones, and plaster them, and write the law on them, and build an altar in the same place, and offer sacrifices when come into the land of Canaan: saying; as follows.