Why has God asked us to honor the Sabbath day? The reasons I think are at least threefold. The first has to do with the physical need for rest and renewing. Obviously God, who created us, would know more than we do of the limits of our physical and nervous energy and strength.
The second reason is, in my opinion, of far greater significance. It has to do with the need for regeneration and the strengthening of our spiritual being. God knows that, left completely to our own devices without regular reminders of our spiritual needs, many would degenerate into the preoccupation of satisfying earthly desires and appetites. This need for physical, mental, and spiritual regeneration is met in large measure by faithful observance of the Sabbath day.
The third reason may be the most important of the three. It has to do with obedience to commandments as an expression of our love for God. Blessed are those who need no reasons other than their love for the Savior to keep his commandments. The response of Adam to the angel who asked Adam why he made a sacrifice unto the Lord is a model for all. Responded Adam, “I know not, save the Lord commanded me.” (Moses 5:6.)
A more recent miracle occurred at the Wells Stake Welfare Tannery some years ago where hides of animals were tanned into leather. On regular workdays, the hides were removed from the vats and fresh lime placed in the vats, after which the hides were returned to the lime solution. If the hides were not turned on holidays, they would spoil. But the change was never made on Sunday, and there were no spoiled hides on Monday. Explained J. Lowell Fox, the supervisor of the tannery at the time:
“This brought a strange fact to our minds: holidays are determined by man, and on these days just as on every week day, the hides need to have special care every twelve hours. Sunday is the day set aside by the Lord as a day of rest, and He makes it possible for us to rest from our labors as He has commanded. The hides at the tannery never spoil on Sundays. This is a modern-day miracle, a miracle that happens every weekend!” (Handbook for Guide Patrol Leaders, Salt Lake City: The Church of Jesus Christ of Latter-day Saints, 1964, p. 37.)