WCF 21.7

As it is of the law of nature that, in general, a due proportion of time be set apart for the worship of God; so, in his Word, by a positive, moral, and perpetual commandment, binding all men in all ages, he hath particularly appointed one day in seven for a Sabbath, to be kept holy unto him:¹ which, from the beginning of the world to the resurrection of Christ, was the last day of the week; and, from the resurrection of Christ, was changed into the first day of the week,² which in Scripture is called the Lord’s day,³ and is to be continued to the end of the world, as the Christian Sabbath.⁴