In Ex. 20:20-23 we find instructions not to have gods of gold and silver; not to build an altar of hewn stone, which would require the use of metal implements; and not to have steps leading up to the altar, which would show the nakedness of those who mounted the steps.
Samson Raphael Hirsch notices that these laws echo the Ten Commandments, with their ban on idolatry, murder and immorality. They also point out three basic features of civilisation – believing in the right things, respecting other people’s lives, and exercising control over your own desires.
Some might see these extra laws as an alternative version of the Ten Commandments, though in that case they would have to be called a Triumvirate, not a Decalogue. They might also be a short version, ten rules reduced to three for easy memorising.
In the light of later history, JH Hertz says that the repetition of these points was “far from unnecessary”.