In Exodus 20, when God speaks to the assembled Children of Israel, it is they who interrupt, telling Moses to speak for God. Moses relates instructions to offer sacrifices and civil laws, which carry the authority of God Himself.
The ‘Ten Commandments’ (which aren’t called that in the Hebrew) were not new. Hearing them coming from God Himself was an admonition that such laws came from God, not just from human reason.
Yes, very interesting. What is the interpretation of Ex. 20:26?