You will not find any Sabbath law outside of Israel. That is how we know that Gentiles were never given the law.
You have been misinformed about who was under the law.
What does the bible say.
Isa 56:2-7
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.
Was it only for the Jews or were the Jews to take it to everyone?
Israel were to be a witness to the world.
And anyone that obeyed was welcome.
"every one that keepeth the sabbath from polluting it, and taketh hold of my covenant;"
Are you part of God's family or a stranger?
Today we are Israelites by adoption. By faith.
Rom 9:8 That is, They which are the children of the flesh, these are not the children of God: but the children of the promise are counted for the seed.
Jesus is the Child of promise. The only child that did not fail and the only child worthy to be called God's son.
We by faith are able to be God's children.
Rom 9:29-32
29 And as Esaias said before, Except the Lord of Sabaoth had left us a seed, we had been as Sodoma, and been made like unto Gomorrha.
30 What shall we say then? That the Gentiles, which followed not after righteousness, have attained to righteousness, even the righteousness which is of faith.
31 But Israel, which followed after the law of righteousness, hath not attained to the law of righteousness.
32 Wherefore? Because they sought it not by faith, but as it were by the works of the law. For they stumbled at that stumblingstone;
If it wasn't for Jesus no one would have a hope.
But the Gentiles by faith have recieved righteousness. The Israelites tried to be righteous by following the law and failed.
So the righteousness that we need is by faith. By faith we are accepted as children of God.
1Co 12:13 For by one Spirit are we all baptized into one body, whether we be Jews or Gentiles, whether we be bond or free; and have been all made to drink into one Spirit.
No distinctions.
If your God's child you should act like Gods child, Jesus. obey not to be saved but because you are a child, by faith act like a child because you love God.
Rom 6:15-16
15 What then? shall we sin, because we are not under the law, but under grace? God forbid. 16 Know ye not, that to whom ye yield yourselves servants to obey, his servants ye are to whom ye obey; whether of sin unto death, or of obedience unto righteousness?