WSC 58-59 -- Fourth Commandment, Part Two - The Change of Day

Question 58: What is required in the fourth commandment?
Answer: The fourth commandment requireth the keeping holy to God such set times as he hath appointed in his word; expressly one whole day in seven, to be a holy sabbath to himself.

Question 59: Which day of the seven hath God appointed to be the weekly sabbath?
Answer: From the beginning of the world to the resurrection of Christ, God appointed the seventh day of the week to be the weekly sabbath; and the first day of the week ever since, to continue to the end of the world, which is the Christian sabbath.