(KJV) Remember the Sabbath day to keep it holy
The fourth commandment in the bible is to keep the Sabbath day to keep it holy. Sabbath is the rest day. Because six days God worked and rest on the seventh day. And God blessed the seventh day and keep it as a holy day.
(Exodus 20:8-11) “You must remember to keep the Sabbath a special day. You may work six days a week to do your job. But the seventh day is a rest day in honor of the Lord your God. So on that day no one should work – not you, your sons and daughters, or your men and women slaves. Even the animals of yours and the foreigners living in your cities must not work! That is because the Lord who is most high worked six days and made the sky, the sea, the earth, and everything in them. And on the seventh day, he rested. And In this way the Lord blessed the Sabbath (worship day) – the day of rest. He made that a very special day.”
You can Read more in detail about the sabbath by reading our article Sabbath for Hebrew is Shabbath.