Exodus 32:15-16, 19

Then Moses went down the mountain, and in his hands he had the two stone tablets with the Agreement on them. The commands were written on both sides of each stone, front and back. God himself had made the tablets, and God himself had written the commands on the tablets.

When Moses came close to the camp, he saw the gold calf and the dancing, and he became very angry. He threw down the stone tablets that he was carrying and broke them at the bottom of the mountain.