https://youtu.be/QEF5Xl8veGQ?si=KzywmgjK4F3bjC6L The sabbath day is the seventh day of the week which is Saturday, according to the ten commandments, in the new testament Jesus and his desciples observed the sabbath day. The bible explained that the sabbath is the day God rested after creating human and things.
In the ten commandments, the fourth one commanded us to keep the sabbath day holy, it says that we have the six days to do everything we had to do within the week, but the sabbath day we should keep it holy.
Jesus as who was a Jewish observed the seventh day being the sabbath day, even after his death and resurrection his desciples continued. Most of the Jewish and some christians continue to observe the sabbath on Saturday. Many christian dominations take Sunday as the day they gather to praise and worship God, the day Jesus resurrected.