The only reference is from John in Rev 1:10. So it is believed to be a practice already when John wrote Revelation. It is a tradition of the first century church that has been passed down. This is what I was taught orally nearly 40 years ago, before google and the internet.
A search of “The Lords Day” -
https://en.wikipedia.org/wiki/Lord's_Day#Textual_tradition
Acts 15:24 KJVS
Forasmuch as we have heard, that certain which went out from us have troubled you with words, subverting your souls, saying, Ye must be circumcised, and keep the law: to whom we gave no such commandment:
Was the Sabbath not part of the Law? Jesus did not observe the Sabbath as understood by the Jews. The Apostles said they didn’t teach this themselves! Paul also clarifies it in Colossians.
Colossians 2:16 KJVS
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
Many serious problems with what you have written, and the first one is that you are presenting church tradition as though it were Scripture. You said that the “Lord’s Day” was a first-century church practice passed down by tradition, but tradition is not proof of what the apostles taught. You yourself admitted that the only Scripture you can point to is Revelation 1:10. That verse does not say Sunday. It does not say the first day of the week. It does not say that the Sabbath was changed. It simply says:
I was in the Spirit on the Lord’s day, and heard behind me a great voice, as of a trumpet. (Revelation 1:10)
If Scripture does not tell us that “the Lord’s Day” means Sunday, then you cannot make the text say something it does not say. The fact that you were taught this orally forty years ago does not turn that teaching into Scripture. We are supposed to test teachings by the Word of God, not use tradition to establish doctrine.
Now you bring up Acts 15:24 and claim that the apostles were saying that they did not teach keeping the Law. But that is not what the passage says. Read the whole matter carefully. The controversy was about Gentiles being told that they had to be circumcised and keep the Law of Moses in order to be saved. The apostles rejected that teaching. They did not announce that the Ten Commandments had been abolished.
Acts 15:24 says:
Since we have heard that some who went out from us have troubled you with words, unsettling your souls, saying, “You must be circumcised and keep the law”—to whom we gave no such commandment
Notice exactly what the apostles rejected:
circumcision and the claim that Gentiles had to take upon themselves the Law of Moses as a requirement for salvation. You have taken that statement and turned it into “therefore the Sabbath commandment no longer exists.” Acts 15:24 never says that.
And you ask, “Was the Sabbath not part of the Law?”
Yes, the Sabbath IS part of the Ten Commandments. But here is where the distinction you are missing becomes very important. The Bible itself distinguishes the Ten Commandments from the other statutes and judgments given through Moses.
God spoke the Ten Commandments directly to Israel, wrote them on tablets of stone, and placed those tablets in the ark. Scripture says:
And He declared to you His covenant which He commanded you to perform, that is, the Ten Commandments; and He wrote them on two tablets of stone. (Deuteronomy 4:13)
The Sabbath is the fourth commandment. So if you claim that the Sabbath commandment was abolished or changed, then you need to show the Scripture where God abolished or changed it.
You cannot simply point to Acts 15:24 and pretend that verse says it. And then you say, “Jesus did not observe the Sabbath as understood by the Jews.” That statement actually proves the opposite of what you are trying to prove.
Jesus did not reject the Sabbath. He rejected the man-made traditions and false interpretations that the religious leaders had added to it.
Jesus said:
The Sabbath was made for man, and not man for the Sabbath. Therefore the Son of Man is also Lord of the Sabbath.(Mark 2:27–28) Notice what Jesus did not say. He did not say, “The Sabbath was made for the Jews only.” He did not say, “The Sabbath is now abolished.” He did not say, “The first day of the week has replaced the seventh day.” men said that and is is NOT based on ANY scripture but only traditions of these same men.
He called Himself
Lord of the Sabbath. And Luke tells us what Jesus actually did:
So He came to Nazareth, where He had been brought up. And as His custom was, He went into the synagogue on the Sabbath day, and stood up to read. (Luke 4:16)
That was Jesus' custom. He followed the sabbath command and explained it further.
So we have a very simple question: are we going to believe what Jesus actually did and taught, or are we going to replace His words with a tradition that says Sunday became the Lord's Day?
Jesus also said:
If you love Me, keep My commandments. (John 14:15)
And:
If you keep My commandments, you will abide in My love, just as I have kept My Father's commandments and abide in His love. (John 15:10)
Jesus did not teach His disciples that obedience to God's commandments was now meaningless. He taught them to keep His commandments, all of them all he taught and He Himself said that He had kept His Father's commandments.
You also mention Colossians 2:16 as though it settles the matter. But even if someone wants to use that passage, they still have to prove what “sabbath days” means in its context. They cannot simply assume that every reference to a Sabbath means the fourth commandment and then declare that commandment abolished. there were many Sabbaths in the old testament
But I will leave that argument aside for now because we do not even need to go there. Jesus' own words already give us the foundation we need.
The bigger problem here is the method being used. You are saying, “I was taught this tradition,” then pointing to a verse that does not actually say what you claim it says, and then declaring that anyone who disagrees is twisting Scripture and that is backwards.
The proper question is not, “What did I hear in church forty years ago?” The proper question is,
“What did Jesus and His apostles actually teach?”
And when we put Jesus' words first, as we should, we find no statement from Him saying that the seventh-day Sabbath was abolished and replaced by Sunday.
There is no verse in Revelation 1:10 saying Sunday.
There is no verse in Acts 15:24 saying the Sabbath was abolished.
There is no statement from Jesus saying the fourth commandment was cancelled.
And there is certainly no command from Jesus saying, “Keep the first day instead.”
I would suggest that we all do write about what is actually written in scripture rather than reading later church tor oral tradition back into the text.
If you can show me one statement from Jesus saying that the Sabbath commandment was abolished, changed to another day, or replaced by Sunday, then present it. Until then, your interpretation does not make it Scripture.
and NO I am not a legalist or SDA but simply follow what Jesus commanded.