The “observe no such thing” was talking about the vow that Paul took.
Think about it: what sense would it make to tell new converts to take a Nazarite vow?
also, you need to go back to Acts 15:21. James gave those commands as a starting point, because Moses was read every Sabbath.
The Gentiles coming into the faith would learn the law of Moses as they gathered with the Body every Sabbath.
the Gentiles coming into the fold were already observing the Sabbath.
Wow, so are you saying that Gentiles are to be circumcised, since you claim that the no such thing applies only to that vow?
The passage reads
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20 And when they heard it, they glorified the Lord, and said unto him, Thou seest, brother, how many thousands of Jews there are which believe; and they are all zealous of the law:
21 And they are informed of thee, that thou teachest all the Jews which are among the Gentiles to forsake Moses, saying that they ought not to circumcise their children, neither to walk after the customs.
22 What is it therefore? the multitude must needs come together: for they will hear that thou art come.
23 Do therefore this that we say to thee: We have four men which have a vow on them;
24 Them take, and purify thyself with them, and be at charges with them, that they may shave their heads: and all may know that those things, whereof they were informed concerning thee, are nothing; but that thou thyself also walkest orderly, and keepest the law.
25
As touching the Gentiles which believe, we have written and concluded that they observe no such thing, save only that they keep themselves from things offered to idols, and from blood, and from strangled, and from fornication.