Here is the first Sunday Law in history, a legal enactment by Constantine 1 (reigned 306-331):
"On the Venerable Day of the Sun ["venerabili die Solis"--the sacred day of the Sun] let the magistrates and people residing in cities rest, and let all workshops be closed. In the country, however, persons engaged in agriculture may freely and lawfully continue their pursuits; because it often happens that another day is not so suitable for grain-sowing or for vine-planting; lest by neglecting the proper moment for such operations the bounty of heaven should be lost…”
Given the 7th day of March, [A.D. 321], Crispus and Constantine being consuls each of them for the second time."--The First Sunday Law of Constantine 1, in "Codex Justinianus," lib. 3, tit. 12, 3; trans. in Phillip Schaff "History of the Christian Church," Vol. 3, p. 380.
Sabbath Judaizers
The Council of Laodicea of around 365 AD decreed 59 laws, #29:
Christians must not Judaize by resting on the Sabbath, but must work on that day, rather honoring the Lord's Day; and, if they can, resting then as Christians. But if any shall be found to be Judaizers, let them be anathema from Christ.
Sabbath and the law
Romans 3:31. KJV
Do we then make void the law through faith? God forbid: yea, we establish the law.
Romans 3:31. NIV
Do we, then, nullify the law by this faith? Not at all! Rather, we uphold the law.
Do you uphold the law by keeping the Sabbath?
There are the laws of God, and there were the laws of the Pharisees. It was the laws and traditions of the Pharisees that Christ spoke against. Knowing the commands of God is a good teacher for living in the spirit of love.
1 John 5:3.
In fact, this is love for God: to keep his commands. And his commands are not burdensome,
2 John 1:6.
And this is love: that we walk in obedience to his commands. As you have heard from the beginning, his command is that you walk in love.
Look, the ones keeping the commandments are the ones getting into heaven.
Revelation 12:17.
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 Yahshua Christ.
Revelation 14:12.
Here is the patience of the saints: here are they that keep the commandments of God, and the faith of Yahshua.
Revelation 22:14.
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.
Christ and the disciples preached the keeping of the commands of God, but yet many who call themselves Christian seem to be teaching another message.
Grace: (In the Christian belief,) the free and unmerited favor of God, as manifested in the salvation of sinners and the bestowal of blessings.
God's grace does not mean that you are to keep sinning by breaking God's commands.
Matthew 4:4.
Yahshua answered, “It is written: ‘Man shall not live on bread alone, but on every word that comes from the mouth of God.’”
Exodus 20:8.
“Remember the Sabbath day by keeping it holy.