Moses
Deuteronomy 27:3KJV·traditional attribution

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.

Matthew Henry Presbyterian

Here is, I. A general charge to the people to keep God's commandments; for in vain did they know them, unless they would do them. This is pressed upon them, 1. With all authority. Moses with the elders of Israel, the rulers of each tribe (Deu 27:1), and again, Moses and the priests the Levites (Deu 27:9); so that the charge is given by Moses...

Commenting on Deuteronomy 27:1-10

John Gill Reformed Baptist

And thou shall write upon them all the words of this law,.... Not the whole book of Deuteronomy, as some think, at least not the historical part of it, only what concerns the laws of God; and it may be only a summary or abstract of them, and perhaps only the ten commandments.

Jamieson-Fausset-Brown Reformed

thou shalt write upon them all the words of this law--It might be, as some think, the Decalogue; but a greater probability is that it was "the blessings and curses," which comprised in fact an epitome of the law (Jos 8:34).