Exo 20:8 Remember the sabbath day, to keep it holy. 9 Six days shalt thou labour, and do all thy work: 10 But the seventh day is the sabbath of the LORD thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates: 11 For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it.

Mat 5:17 Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil. 18 For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled. 19 Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called the least in the kingdom of heaven: but whosoever shall do and teach them, the same shall be called great in the kingdom of heaven. 20 For I say unto you, That except your righteousness shall exceed the righteousness of the scribes and Pharisees, ye shall in no case enter into the kingdom of heaven.

THE CATECHISM OF THE CATHOLIC CHURCH.

“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.

A day of grace and rest from work

2184 Just as God “rested on the seventh day from all his work which he had done,”[121] human life has a rhythm of work and rest. The institution of the Lord’s Day helps everyone enjoy adequate rest and leisure to cultivate their familial, cultural, social, and religious lives.[122]

2185 On Sundays and other holy days of obligation, the faithful are to refrain from engaging in work or activities that hinder the worship owed to God, the joy proper to the Lord’s Day, the performance of the works of mercy, and the appropriate relaxation of mind and body.[123] Family needs or important social service can legitimately excuse from the obligation of Sunday rest. The faithful should see to it that legitimate excuses do not lead to habits prejudicial to religion, family life, and health. 
The charity of truth seeks holy leisure- the necessity of charity accepts just work.[124]

2186 Those Christians who have leisure should be mindful of their brethren who have the same needs and the same rights, yet cannot rest from work because of poverty and misery. Sunday is traditionally consecrated by Christian piety to good works and humble service of the sick, the infirm, and the elderly. Christians will also sanctify Sunday by devoting time and care to their families and relatives, often difficult to do on other days of the week. Sunday is a time for reflection, silence, cultivation of the mind, and meditation which furthers the growth of the Christian interior life.

2187 Sanctifying Sundays and holy days requires a common effort. Every Christian should avoid making unnecessary demands on others that would hinder them from observing the Lord’s Day. Traditional activities (sport, restaurants, etc.), and social necessities (public services, etc.), require some people to work on Sundays, but everyone should still take care to set aside sufficient time for leisure. With temperance and charity the faithful will see to it that they avoid the excesses and violence sometimes associated with popular leisure activities. In spite of economic constraints, public authorities should ensure citizens a time intended for rest and divine worship. Employers have a similar obligation toward their employees.

2188 In respecting religious liberty and the common good of all, Christians should seek recognition of Sundays and the Church’s holy days as legal holidays. They have to give everyone a public example of prayer, respect, and joy and defend their traditions as a precious contribution to the spiritual life of society. If a country’s legislation or other reasons require work on Sunday, the day should nevertheless be lived as the day of our deliverance which lets us share in this “festal gathering,” this “assembly of the firstborn who are enrolled in heaven.”[125]

IN BRIEF

2189 “Observe the sabbath day, to keep it holy” (Deut 5:12). “The seventh day is a sabbath of solemn rest, holy to the Lord” (Ex 31:15).

2190 The sabbath, which represented the completion of the first creation, has been replaced by Sunday which recalls the new creation inaugurated by the Resurrection of Christ.

2191 The Church celebrates the day of Christ’s Resurrection on the “eighth day,” Sunday, which is rightly called the Lord’s Day (cf. SC 106).

2192 “Sunday . . . is to be observed as the foremost holy day of obligation in the universal Church” (CIC, can. 1246 # 1). “On Sundays and other holy days of obligation the faithful are bound to participate in the Mass” (CIC, can. 1247).

2193 “On Sundays and other holy days of obligation the faithful are bound . . . to abstain from those labors and business concerns which impede the worship to be rendered to God, the joy which is proper to the Lord’s Day, or the proper relaxation of mind and body” (CIC, can. 1247).

2194 The institution of Sunday helps all “to be allowed sufficient rest and leisure to cultivate their amilial, cultural, social, and religious lives” (GS 67 # 3).

2195 Every Christian should avoid making unnecessary demands on others that would hinder them from observing the Lord’s Day.”

Choose you this day whom you will serve.

THE WORD OF GOD

Isa 56:1 Thus saith the LORD, Keep ye judgment, and do justice: for my salvation is near to come, and my righteousness to be revealed. 2 Blessed is the man that doeth this, and the son of man that layeth hold on it; that keepeth the sabbath from polluting it, and keepeth his hand from doing any evil. 3 Neither let the son of the stranger, that hath joined himself to the LORD, speak, saying, The LORD hath utterly separated me from his people: neither let the eunuch say, Behold, I am a dry tree. 4 For thus saith the LORD unto the eunuchs that keep my sabbaths, and choose the things that please me, and take hold of my covenant; 5 Even unto them will I give in mine house and within my walls a place and a name better than of sons and of daughters: I will give them an everlasting name, that shall not be cut off. 6 Also the sons of the stranger, that join themselves to the LORD, to serve him, and to love the name of the LORD, to be his servants, every one that keepeth the sabbath from polluting it, and taketh hold of my covenant; 7 Even them will I bring to my holy mountain, and make them joyful in my house of prayer: their burnt offerings and their sacrifices shall be accepted upon mine altar; for mine house shall be called an house of prayer for all people. 8 The Lord GOD which gathereth the outcasts of Israel saith, Yet will I gather others to him, beside those that are gathered unto him.

Rev 12:15 And the serpent cast out of his mouth water as a flood after the woman, that he might cause her to be carried away of the flood. 16 And the earth helped the woman, and the earth opened her mouth, and swallowed up the flood which the dragon cast out of his mouth. 17 And the dragon was wroth with the woman, and went to make war with the remnant of her seed, which keep the commandments of God, and have the testimony of Jesus Christ.

Rev 14:12 Here is the patience of the saints: here are they that keep the commandments of God, and the faith of Jesus.

Rev 22:13 I am Alpha and Omega, the beginning and the end, the first and the last. 14 Blessed are they that do his commandments, that they may have right to the tree of life, and may enter in through the gates into the city. 15 For without are dogs, and sorcerers, and whoremongers, and murderers, and idolaters, and whosoever loveth and maketh a lie.