2168 The third commandment of the Decalogue recalls the holiness of the sabbath: "The seventh day is a sabbath of solemn rest, holy to the LORD."92
2169 In speaking of the sabbath Scripture recalls creation: "For in six days the LORD made heaven and earth, the sea, and all that is in them, and rested the seventh day; therefore the Lord blessed the sabbath day and hallowed it."93
2170 Scripture also reveals in the Lord’s day a memorial of Israel’s liberation from bondage in Egypt: "You shall remember that you were a servant in the land of Egypt, and the LORD your God brought you out thence with mighty hand and outstretched arm; therefore the LORD your God commanded you to keep the sabbath day."94
2171 God entrusted the sabbath to Israel to keep as a sign of the irrevocable covenant.95 The sabbath is for the Lord, holy and set apart for the praise of God, his work of creation, and his saving actions on behalf of Israel.
2172 God’s action is the model for human action. If God “rested and was refreshed” on the seventh day, man too ought to “rest” and should let others, especially the poor, "be refreshed."96 The sabbath brings everyday work to a halt and provides a respite. It is a day of protest against the servitude of work and the worship of money.97
2173 The Gospel reports many incidents when Jesus was accused of violating the sabbath law. But Jesus never fails to respect the holiness of this day.98 He gives this law its authentic and authoritative interpretation: "The sabbath was made for man, not man for the sabbath."99 With compassion, Christ declares the sabbath for doing good rather than harm, for saving life rather than killing.100 The sabbath is the day of the Lord of mercies and a day to honor God.101 "The Son of Man is lord even of the sabbath."102
II. THE LORD’S DAY
This is the day which the LORD has made; let us rejoice and be glad in it.103
The day of the Resurrection: the new creation
2174 Jesus rose from the dead "on the first day of the week."104 Because it is the “first day,” the day of Christ’s Resurrection recalls the first creation. Because it is the “eighth day” following the sabbath,105 it symbolizes the new creation ushered in by Christ’s Resurrection. For Christians it has become the first of all days, the first of all feasts, the Lord’s Day (he kuriake hemera, dies dominica) Sunday:
We all gather on the day of the sun, for it is the first day [after the Jewish sabbath, but also the first day] when God, separating matter from darkness, made the world; and on this same day Jesus Christ our Savior rose from the dead.106
Sunday - fulfillment of the sabbath
2175 Sunday is expressly distinguished from the sabbath which it follows chronologically every week; for Christians its ceremonial observance replaces that of the sabbath. In Christ’s Passover, Sunday fulfills the spiritual truth of the Jewish sabbath and announces man’s eternal rest in God. For worship under the Law prepared for the mystery of Christ, and what was done there prefigured some aspects of Christ:107
Those who lived according to the old order of things have come to a new hope, no longer keeping the sabbath, but the Lord’s Day, in which our life is blessed by him and by his death.108
2176 The celebration of Sunday observes the moral commandment inscribed by nature in the human heart to render to God an outward, visible, public, and regular worship "as a sign of his universal beneficence to all."109 Sunday worship fulfills the moral command of the Old Covenant, taking up its rhythm and spirit in the weekly celebration of the Creator and Redeemer of his people.