Exodus 32:15-16, 19

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. Now the tablets were the work of God, and the writing was the writing of God engraved on the tablets.

So it was, as soon as he came near the camp, that he saw the calf and the dancing. So Moses’ anger became hot, and he cast the tablets out of his hands and broke them at the foot of the mountain.