All of these can be answered by reading scripture.
What did God say?
Genesis 26:4-5 And I will make thy seed to multiply as the stars of heaven, and will give unto thy seed all these countries; and in thy seed shall all the nations of the earth be blessed; Because that Abraham obeyed my voice, and kept my charge, my commandments, my statutes, and my laws.
What did God say?
Exodus 31:16 Wherefore the children of Israel shall keep the sabbath, to observe the sabbath throughout their generations, for a perpetual covenant.
What did Paul say?
Galatians 3:28 There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female: for ye are all one in Christ Jesus.
What did Jesus say?
Matthew 24:19-20 But pray ye that your flight be not in the winter, neither on the sabbath day: For then shall be great tribulation, such as was not since the beginning of the world to this time, no, nor ever shall be.
What did the Revelation of Jesus Christ say?
This is Jesus from heaven.
Revelation 1:1-2 The Revelation of Jesus Christ, which God gave unto him, to shew unto his servants things which must shortly come to pass; and he sent and signified it by his angel unto his servant John: Who bare record of the word of God, and of the testimony of Jesus Christ, and of all things that he saw.
This is the last call to worship before Jesus returns.
Revelation 14:6-7 And I saw another angel fly in the midst of heaven, having the everlasting gospel to preach unto them that dwell on the earth, and to every nation, and kindred, and tongue, and people, Saying with a loud voice, Fear God, and give glory to him; for the hour of his judgment is come: and worship him that made heaven, and earth, and the sea, and the fountains of waters.
↓ ↓ Points to creation concerning worship where we find the Sabbath instituted
Genesis 2:1-3 Thus the heavens and the earth were finished, and all the host of them. And on the seventh day God ended his work which he had made; and he rested on the seventh day from all his work which he had made. And God blessed the seventh day, and sanctified it: because that in it he had rested from all his work which God created and made.
↑ ↑ Points to creation concerning the Sabbath where we find the Sabbath instituted.
Exodus 20:8-11 Remember the sabbath day, to keep it holy. Six days shalt thou labour, and do all thy work: 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: 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.
The Sabbath is specifically mentioned as the day the apostles would preach to the Gentiles. The very keeping of the Sabbath by the apostles in their preaching on the Sabbath was teaching the Gentiles to keep the Sabbath, and there is proof of this in Acts as the Gentiles asked to be preached to on the next Sabbath.
Acts 13:42-44 And when the Jews were gone out of the synagogue, the Gentiles besought that these words might be preached to them the next sabbath. Now when the congregation was broken up, many of the Jews and religious proselytes followed Paul and Barnabas: who, speaking to them, persuaded them to continue in the grace of God. And the next sabbath day came almost the whole city together to hear the word of God.
The Sabbath was instituted at creation. Adam and Eve weren't Jews. Abraham wasn't a Jew. If Abraham is recorded as keeping God's commandments, then the Sabbath was being kept up to Abraham which is before there was such a thing as Israel or Jews.
Colossians 2: Let no man judge you...
Colossians 2:16 Let no man therefore judge you in meat, or in drink, or in respect of an holyday, or of the new moon, or of the sabbath days.
What sabbath days is Paul talking about?
Look at the full context.
Colossians 2:14 Blotting out the handwriting of ordinances that was against us, which was contrary to us, and took it out of the way, nailing it to his cross.
The handwriting of ordinances that was against us is mentioned in Deuteronomy 31:26 as being put beside the ark, not in it where the tables of stone were kept.
Deuteronomy 31:26 Take this book of the law, and put it in the side of the ark of the covenant of the Lord your God, that it may be there for a witness against thee.
This was the book of the law, the handwriting of ordinances, not the Ten commandments. Further proof.
Colossians 2:17 Which are a shadow of things to come; but the body is of Christ.
The handwriting of ordinances was a shadow of things to come. The sabbath days mentioned are the days in the handwriting of ordinances, not the Sabbath commandment.
Even if you could link the Sabbath commandment, the statement is not negating the Sabbath, it is saying to not let others judge you for
keeping it (see
the Amplified translation of the verse), which negates the idea that it is doing away with the Sabbath altogether.
Romans 14: One man esteemeth one day above another...
Romans 14:1-8 Him that is weak in the faith receive ye, but not to doubtful disputations. For one believeth that he may eat all things: another, who is weak, eateth herbs. Let not him that eateth despise him that eateth not; and let not him which eateth not judge him that eateth: for God hath received him. Who art thou that judgest another man's servant? to his own master he standeth or falleth. Yea, he shall be holden up: for God is able to make him stand. One man esteemeth one day above another: another esteemeth every day alike. Let every man be fully persuaded in his own mind. He that regardeth the day, regardeth it unto the Lord; and he that regardeth not the day, to the Lord he doth not regard it. He that eateth, eateth to the Lord, for he giveth God thanks; and he that eateth not, to the Lord he eateth not, and giveth God thanks. For none of us liveth to himself, and no man dieth to himself. For whether we live, we live unto the Lord; and whether we die, we die unto the Lord: whether we live therefore, or die, we are the Lord's.
The subject of Romans 14 is the judging of others, to the point of imposing your will on their conscience. Each person's conscience is their own. As it says, "Let every man be fully pursuaded in his own mind." The freedom of choice is given to all of us, based on our own conscience. The Sabbath commandment is not negated whatsoever by Romans 14.
If we are called to keep the commandments of God, and the Sabbath is one of those Ten commandments, then we are indeed directed to observe the Sabbath. As Exodus says, the Sabbath is a perpetual covenant for Israel. Israel includes the Gentiles. See Romans 11 where we are grafted in.
What changed in your example? The Isrealites sinned against God. God's standard didn't change. It has never changed.
Read the preceding verses.
2 Corinthians 3:1-3 Do we begin again to commend ourselves? Or do we need, as some others, epistles of commendation to you or letters of commendation from you? You are our epistle written in our hearts, known and read by all men; clearly you are an epistle of Christ, ministered by us, written not with ink but by the Spirit of the living God, not on tablets of stone but on tablets of flesh, that is, of the heart.
Tablets of flesh, that is, of the heart. Where else do we find this?
Jeremiah 31:33 But this is the covenant that I will make with the house of Israel after those days, says the Lord: I will put My law in their minds, and write it on their hearts; and I will be their God, and they shall be My people.
Hebrews 8:10 For this is the covenant that I will make with the house of Israel after those days, says the Lord: I will put My laws in their mind and write them on their hearts; and I will be their God, and they shall be My people.
Hebrews 10:16-17 “This is the covenant that I will make with them after those days, says the Lord: I will put My laws into their hearts, and in their minds I will write them,” then He adds, “Their sins and their lawless deeds I will remember no more.”
The law wasn't done away with. The law is written in the heart in the new covenant.