I don’t know every body know this or not. Just one to share, because I taugth catechism before, and taught the children about this.
Sabbath is acutally Saturday. If follow the Jewish custom, it is from Friday sunset until Saturday sunset. Because, for Jewish, a day start from sunset. That is why we celebrate sunset mass on Saturday and it fulfils the Sunday obligation. And, Sabbath is the day of rest.
Why Sabbath is the day of rest? I don’t know why. But this is a marvellous thing. We know God created the world using 7 days, and Sabbath day is the 7th day. On the 6th day God created the human beings, and Jesus on Friday (6th day) suffered for human beings. God rested on the 7th day, and Jesus rested in the tomb on Saturday. Then on Sunday, Jesus raised from the dead, which the Sunday is the 1st day of creation, and Jesus re-created the whole world through His resurrection.
How nice it is.