On both their sides Thus it was effectually provided against a possibility of any one either taking from or adding to this law, to do either of which God expressly forbade his people, Deuteronomy 4:2. The tables were the work of God Herein they differed from the second tables, which were the work of Moses, Exodus 34:1.
Related Commentaries of Exodus 32:15
Exodus 32:15-16
15 And Moses turned, and went down from the mount, and the two tables of the testimony were in his hand: the tables were written on both their sides; on the one side and on the other were they written.
16 And the tables were the work of God, and the writing was the writing of God, graven upon the tables.