Charles Bradford notes in his book Sabbath Roots: The African Connection that:
Sabbath is a promise of heavenly rest, a gift that brings with it a token or pledge of life in the escheton, the kingdom of God. It is God’s future experienced in the now. A portion of eternity set in the midst of time.
The Sabbath is promise, but it is experienced now. The Sabbath is the Kingdom of God experienced and brought to today. The Sabbath is our ability to catch a glimpse of what the future Kingdom will be about. The Sabbath is our proof that the future Kingdom will come to past. We are certainly called to talk about and preach that Sabbath.