Q. 66. What is the reason annexed to the fifth commandment?
A. The reason annexed to the fifth commandment is a promise of long life and prosperity (as far as it shall serve for God’s glory and their own good) to all such as keep this commandment.
— Westminster Shorter Catechism
Q. 60. How is the sabbath to be sanctified?
A. The sabbath is to be sanctified by a holy resting all that day, even from such worldly employments and recreations as are lawful on other days; and spending the whole time in the public and private exercises of God's worship, except so much as is to be taken up in the works of necessity and mercy.
Westminster Shorter Catechism