Deuteronomy 27:9-10

The new generation of Israelites would become a people for Yahweh (Deuteronomy 27:9) when they took on themselves the responsibilities and privileges of the Mosaic Law (Deuteronomy 27:10). As their fathers had done at Mt. Horeb (Exodus 19:8), so the new generation would do at Mt. Ebal.

"The ceremonial feast was usually part of the ratification activities when suzerainty treaties were signed in countries neighboring Israel during the Mosaic era." [Note: Schultz, p. 85.]

"This day" (Deuteronomy 27:9) refers to the day the people would fulfill these instructions in the land (Joshua 8; cf. Joshua 24).