first mention of the sabbath in the bible
Biblical Sabbath Observation and remembrance of Sabbath is one of the Ten Commandments (the fourth in the original Jewish, the Eastern Orthodox, and most Protestant traditions, the third in Roman Catholic and Lutheran traditions), sometimes referred to individually as the Sabbath Commandment. Most people who observe Biblical Sabbath regard it as having been made for man (Mark. 2:27) at Creation (Ex. 20:8–11), and instituted as a perpetual covenant for the people of Israel (Ex. 31:13-17, Ex. 23:12, Deut. 5:13-14), a rule that also applies to proselytes, and a sign respecting two events: the seventh day, during which God rested after having completed Creation in six days (Gen. 2:2-3, Ex. 20:8-11), and God's deliverance of the Israelites from Egypt (Deut. 5:12-15).
Lord's Day According to some sources, Christians held corporate worship on Sunday in the 1st century.[1] The earliest Biblical example of Christians meeting together on a Sunday for the purpose of "breaking bread" and preaching is cited in the New Testament book The Acts of the Apostles chapter 20 and verse 7 (Acts 20:7). 2nd-century writers such as Justin Martyr attest to the widespread practice of Sunday worship (First Apology, chapter 67), and by 361 AD it had become a mandated weekly occurrence. During the Middle Ages, Sunday worship became associated with Sabbatarian (rest) practices. Some Protestants today (particularly those theologically descended from the Puritans) regard Sunday as Christian Sabbath, a practice known as first-day Sabbatarianism. (Some Christian groups hold that the term "Lord's Day" can only properly refer to seventh-day Sabbath or Saturday.)