Moreover I gave them my sabbaths, as a sign between me and them, that they might know that I the Lord sanctify them. Eze. 20:12, R.S.V.
People from many cultures have found it helpful to come up with some kind of "shorthand" to define how one ought to relate to new acquaintances of the opposite sex. A man wants to know, for example, if a woman is available for further friendship or whether she already belongs to someone else. Most Western societies have adopted the wedding ring for this purpose. While as a symbol it has often been abused, at least it can be a quick way of saying "I belong to someone!"
Since "belonging to God" is the essence of true spirituality, God wanted to give His people a meaningful symbol by which they could tell the world. "We belong to our Lord!" Even more than just a symbol of belonging, God wanted that experience actually to deepen the value of belonging. And so God repeatedly gave to His people the very thing He had given them in the garden: He gave them time--sacred time, set aside from all lesser distractions, just to enjoy fellowship with their heavenly Father.
I know of several husbands who regularly take their wives on "dates," special times alone, even after they have been married for many years. When they turn down other invitations because they say, "I have a date with my wife!" their friends know that they have a very rich relationship going between them.
That is precisely what God had in mind with the Sabbath. He wanted His people to be known worldwide as being unavailable for other appointments on the Sabbath because they were so joyously engrossed with the One to whom they belonged. Sadly, He had to report that "my sabbaths they greatly profaned" (Eze. 20:13, R.S.V.). They gave counterfeit messages with the Sabbath, flaunting it as a sign of belonging, while their hearts were far away from Him. Or they became absorbed in the ritual itself to the exclusion of the relationship.
In the final showdown of history, those who remain loyal to God will have discovered the joys and meaningful symbolism of this sign of belonging. They will be living out God's desire to "hallow my sabbaths that they may be a sign between me and you, that you may know that I am the Lord your God" (verse 20).