Sabbath is a rhythm of rest in which we lay down our work and our worries to delight in God and celebrate His love. Sabbath has as its purpose rest, restoration, and renewal as expressed in the commands for Sabbath, Sabbatical year, and Jubilee (which is more explicit toward restoration). It is an opportunity to let God be God by following His example (Gen 2:2-3; Ex 20:11; Lev. 25:10-15) and a chance to practice living in the freedom we have in Christ (Deut 5:15; Mark 2:27; Gal 5:1, 13).
For more on Sabbath:
Book: The Rest of God by Mark Buchanan