Seventh-Day Adventist Beliefs: The Sabbath
The beneficent Creator, after the six days of Creation, rested on the seventh day and instituted the Sabbath for all people as a memorial of Creation. The fourth commandment of God's unchangeable law requires the observance of this seventh-day Sabbath as the day of rest, worship, and ministry in harmony with the teaching and practice of Jesus, the Lord of the Sabbath. The Sabbath is a day of delightful communion with God and one another. It is a symbol of our redemption in Christ, a sign of our sanctification, a token of our allegiance, and a foretaste of our eternal future in God's kingdom. The Sabbath is God's perpetual sign of His eternal covenant between Him and His people. Joyful observance of this holy time from evening to evening, sunset to sunset, is a celebration of God's creative and redemptive acts.
--Fundamental Beliefs, 19
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I should probably mention, since they keep doing wacky things with the calendars, that the Sabbath in question refers to Saturday. The "evening to evening, sunset to sunset" emphasizes that this is a continuation of the original Jewish Sabbath.