The Law of God is Eternal
God has already achieved perfection.
Be ye therefore perfect, even as your Father which is in heaven is perfect.
- Matthew 5:48 (KJV)
As a result, God does not change, and nor do His commandments.
The law of God existed before man was created. It was adapted to the condition of holy beings; even angels were governed by it. After the Fall, the principles of righteousness were unchanged. Nothing was taken from the law; not one of its holy precepts could be improved. And as it has existed from the beginning, so will it continue to exist throughout the ceaseless ages of eternity. "Concerning thy testimonies," says the psalmist, "I have known of old that thou hast founded them for ever" (Psalms 119:152).
- Ellen White, Selected Messages Book One, p. 220
That's why the Sabbath today is still in place.