The Sabbath day!
God Almighty worked six days and rested on the seventh day. Did God need to rest? I'm quite sure He didn't, but He did so to establish for posterity a spiritual principle and a human principle: rest is sacred.
Here we have a principle written down that we must put into practice: rest from all the hours of our labors. That is, we must set aside a time for the Lord, to meditate on His word, to wash and worship Him, to be with others who share the same faith. Here the Lord speaks of a special day: the Sabbath.
Most of the time, we live overwhelmed, with so many tasks, studying, work, meetings, and so many other things that consume our time, and we don't have time to rest. We don't make or set aside that time for the Lord. Today, God urges us to set aside our time to dedicate to Him.
And on the seventh day, God finished His work which He had been doing; and He rested on the seventh day from all His work which He had been doing. 3 And God blessed the seventh day and hallowed it, because on it he rested from all the work of creating which he had done.
Genesis 2:2-3