Deuteronomy 27:3

(b) And thou shalt write upon them all the words of this law, when thou art passed over, that thou mayest go in unto the land which the LORD thy God giveth thee, a land that floweth with milk and honey; as the LORD God of thy fathers hath promised thee.

(b) God would have his law set up in the borders of the land of Canaan, that all that looked on it might know that the land was dedicated to his service.