The Sabbath is the weekly day of rest, and is a day of holy convocation. God calls His people to assemble to worship Him on this day. We find this stated in Leviticus 23:3.
“Six days shall work be done, but on the seventh day is a Sabbath of solemn rest, a holy convocation. You shall do no work. It is a Sabbath to the LORD in all your dwelling places.” (Lev. 23:3)The sabbath day in the Old Testament was based on God’s works of creation and redemption on the seventh day (Exod. 20:11; Deut. 5:15). But the day of the new creation and the day of redemption in the New Testament is the first day of the week, the day Jesus rose from the dead. Thus, our observance of the Sabbath and its “holy convocation” also shifts to the first day. The fourth commandment was not abrogated, but its old covenant form was replaced by its new covenant form, explicitly connected to the work of Christ.
This shift was taught by the example of our Lord - it was not a mere invention of the church. Jesus met with his disciples on the day of His resurrection and broke bread with some of them (Luke 24, John 20:19-23). A week later, on the first day of the week, they were gathered again and He met with them again (John 20:26-29). Seven weeks later, on the first day of the week, was the day of Pentecost (Lev. 23:15-16), when the disciples were gathered again in one place and the Spirit descended upon them in the morning (Acts 2:1ff). They spoke in foreign tongues and Peter preached.
Following this, we find the apostles following this example and gathering on the first day of the week. Later in Acts 20:7 we find that “on the first day of the week” they “were gathered together to break bread” and “Paul talked with them…and he prolonged his speech until midnight.” In 1 Corinthians 11 we find that the Corinthian church gathered together as a church to eat the Lord’s Supper (11:18, 20, 33), and in 1 Corinthians 16 we find that this day that they met together was the first day of the week, since Paul tells them to collect supplies for the Jerusalem church on “the first day of every week” (16:2). Finally, we find that the Apostle John received God’s word on the “Lord’s Day” in Revelation 1:10, a reference to the first day of the week, the day of the Lord’s resurrection.
The early church continued to gather on this day, as Justin Martyr records in A.D. 155: “We all make our assembly in common on Sunday, since it is the first day, on which God changed the darkness and matter and made the world, and Jesus Christ our Savior arose from the dead on the same day” (Justin Martyr, First Apology).
While there is more to the Christian Sabbath than worship, we can see that worship is a very important part of it, even central. It is a day of rest and worship, a feast day in commemoration of Jesus’ resurrection. It is a day of convocation, a day to worship with God’s people, a day to partake of the Lord’s Supper and to meet with the triune God.