Which Day Is the Christian Sabbath According to the Bible?

To help you learn the importance and meaning of the Sabbath get our Free Book: "Which Day Is the Christian Sabbath?" https://bit.ly/3mPt5PD Why is this free? We are determined to follow Jesus’ command to "freely give" (Matthew 10:8).

More than two billion professing Christians observe Sunday as their day of worship.
And yet, millions of others observe Saturday, the seventh day of the week, as their day of worship.

Which day truly is the Christian Sabbath?