Exodus:32:15-16
nkjv@Exodus:32:15 @ And Moses turned and went down from the mountain, and the two tablets of the Testimony were in his hand. The tablets were written on both sides; on the one side and on the other they were written.
nkjv@Exodus:32:16 @ Now the tablets were the work of God, and the writing was the writing of God engraved on the tablets.