In ancient times servants and serfs were required to wear garments similar to what their master wore. Wearing such look-alike garments was known as dressing in livery.
In our first reading today, God ordered Moses to remind the people;e of their obligation to do what he does.
God says we must be holy because he, the Lord, am holy.
You must not swear falsely because I would not. And, I am your Lord.
You should not defied your neighbor, or withheld wages, or curse the deaf, because I would not to much thing, and you must imitate me, because I am the Lord.