God wrote the Law on a second set of stone tablets.
During the golden calf incident, Moses threw down and broke the first set of stone tablets containing the Law.
With intercession, punishment, forgiveness, and restoration complete, GOD told Moses to cut out a new set of stone tablets so that He could rewrite the Law.
1 Now the Lord said to Moses, “Cut two tablets of stone like the first ones, and I will write on these tablets the words that were on the first tablets you broke. 2 So be ready in the morning to come up on Mount Sinai and to present yourself to Me there on top of the mountain. 3 But no man shall come up with you, and let no man be seen throughout all the mountain; let neither sheep nor oxen feed before that mountain.” 4 So he cut two tablets of stone like the first ones. Then Moses rose early in the morning and went up to Mount Sinai as the Lord commanded him; and he took in his hand the two tablets of stone.
27 Again the Lord said to Moses, “Write these words for yourself, for according to these words I established a covenant with you and with Israel.” 28 So he was there with the Lord forty days and forty nights; he neither ate bread nor drank water. He wrote on the tablets the words of the covenant, the Ten Commandments.
(Exodus 34:1-4, 27-28 OSB)
The stone tablets served as an important reminder for Israel of the ten commandments, the Law, and GOD's personal delivery of them to Israel. They were proof of Israel's past.