How many Commandments were on each of Moses tablets?

I know it's maybe not the most important thing in Christianity but I still got curious. We know that Moses got from God two tablets with the Ten Commandments. So how many Commandments were on each tablet? I searched the internet and most answers are that there were 5 Commandments on the first tablet and 5 on the second one. I didn't find any good proof for it, however. And on some old art, there are actually 3 Commandments on the first tablet and 7 on the second one, for example: - [Moses holding the Ten Commandments](https://www.dreamstime.com/stock-photo-moses-holding-ten-commandments-painting-church-altar-image90219428) - [Why Is Counting the Ten Commandments So Difficult?](https://blog.lexhampress.com/2020/02/06/why-is-counting-the-ten-commandments-so-difficult/) What is the tradition and reason for depicting the tablets this way?