If you did you'd know where in the New Testament was see the Apostles meeting on the first day of the week (Sunday)
Since when does meeting on any given day of the week (OT or NT) replace a stated commandment of God (Exodus 20:8-11 KJB)? Why would a person conclude such? What are you assuming (incorrectly) by such an untenable position?
My book addresses this claim also.
In the Bible, in the OT and NT, there are texts which some attempt to utilize to say that there was a change in the solemnity of the 7th day to that of the first [day] of the week, and the following texts are often pointed to as ‘proving’ such to be the case:
Genesis 1:5 KJB - ... the first day.
Genesis 1:5 HOT - ... יום אחד׃
Matthew 28:1 KJB - ... the first day of the week, ...
Matthew 28:1 GNT TR - ... εις μιαν σαββατων ...
Mark 16:2 KJB - ... the first day of the week, ...
Mark 16:2 GNT TR -... πρωι της μιας σαββατων ...
Mark 16:9 KJB - ... the first day of the week, ...
Mark 16:9 GNT TR - ... πρωι πρωτη σαββατου ...
Luke 24:1 KJB - ... the first day of the week, ...
Luke 24:1 GNT TR - ... μια των σαββατων ...
John 20:1 KJB - The first day of the week ...
John 20:1 GNT TR - τη δε μια των σαββατων ...
John 20:19 KJB - ... the first day of the week, ...
John 20:19 GNT TR - ... τη μια των σαββατων ...
Acts 2:1 KJB - ... the day of Pentecost was fully come, ... (Pentecost, mathematically took place upon the first day of the week, being 50 days from firstfruits / wavesheaf, or Jesus’ resurrection.)
Acts 2:1 GNT TR - ... τω συμπληρουσθαι την ημεραν της πεντηκοστης ...
Acts 20:7 KJB - ... the first day of the week, ...
Acts 20:7 GNT TR - ... τη μια των σαββατων ...
1 Corinthians 16:2 KJB - ... the first day of the week ...
1 Corinthians 16:2 GNT TR - ... μιαν σαββατων ...
Revelation 1:10 KJB - ... the Lord’s day, ... (Some assume this text refers to the first day, but it does not, as shall be seen in a bit.)
Revelation 1:10 GNT TR - ... τη κυριακη ημερα ...
Consider the true evaluation of those texts (in brief, or see the individual chapters on each text in detail):
The text of Gen. 1:5 refers to the first day of the creation of this world, and has nothing to do with any supposed transfer of the solemnity of the 7th day to that of the 1st day. It was a day of God’s working, not one of rest by God (Gen. 2:1-3 KJB).
The text of Mat. 28:1(a) is the closing of the still existing 7th day sabbath, or the Lord’s day (Isa. 58:13; Rev. 1:10 KJB), and demonstrates that the 7th day the sabbath still exists and recurs weekly to be kept “holy” (Exo. 20:8-11 KJB), and was kept so by the disciples of Jesus (Luk. 23:54,56 KJB) even after He died.
The text of Mat. 28:1(b) refers to the first (μιαν) week which begins the 7 sabbaths (σαββατων, plural), or 49 days +1, unto Pentecost (Act. 2:1 KJB). This is not a weekly, recurring, referral to the first day of the week, but instead refers to the first day, or even week, that begins the counting towards the antitypical (or true, real) Pentecost. In the Old Testament, this referred to only a single day in the year, which did not recur that year.
The texts of Mar. 16:2,9; Luk. 24:1; Jhn. 20:1 KJB (“πρωι της μιας σαββατων”, “πρωι πρωτη σαββατου”, “μια των σαββατων”, “τη δε μια των σαββατων”) are the exact same first ‘day’, or week, of sabbaths, as Mat 28:1(b), referring to the days of the 7 sabbaths counting up towards the culmination of Pentecost (Feast of Weeks; Lev. 23:15-22 KJB). These are all the same non-recurring day as Mat. 28:1(b).
The text of Jhn. 20:19 KJB actually refers to the evening (dark) portion which begins the second day of the week (Luk. 24:13-36 KJB; it was dark when Jesus secretly entered with the two from Emmaus; Luk. 24:13 KJB), but still in the first week of sabbaths of the 7 sabbaths toward Pentecost (Act. 2:1 KJB). It began as a “sad” (Luk. 24:17 KJB), “sorrowful” (Jhn. 16:20,22 KJB) day, and of the “fear of the Jews” (Jhn. 20:19 KJB). A Great Disappointment had taken place, and would be repeated later (Rev. 10:10 KJB).
The text of Jhn. 20:26 actually refers to the third (inclusive) or fourth (exclusive) day of the week (the counting begun from the evening portion of the second day of the week in Luk. 24:36; Jhn. 20:19; being nine days (after 8 days) previous) in that second week of sabbaths of the 7 sabbaths toward Pentecost. This day was, like the others, non-recurring.
The text of Act. 20:7 refers to the evening (night) portion of the first ‘day’, or week, of sabbaths (“τη μια των σαββατων”) in the 7 sabbaths unto Pentecost, and the meeting lasted unto midnight, where an event occurred with Eutychus (and then continued to early morning before sunrise). This was a one-time special farewell to Paul, after the sabbath was over, again in another counting of weeks towards another Pentecost (Act. 12:4, 18:21 KJB), for he had been going around confirming the churches before he returned to Jerusalem to be able to preach to the crowds of Jews that would come from all over. More will be given on this in a bit.
The text of 1 Cor. 16:2 refers to Paul’s instructions regarding the special collection (not tithes, or regular offerings, which are both still required) for the poor in Jerusalem because of the dearth foretold by Agabus, which was to be personally gathered at home after the Sabbath was over, on the first day of week when business was conducted. No one met together at all in 1 Cor. 16:1-2, but instead they individually remained at home.
The text of Act. 2:1 is the 50th day from First Fruits (when Jesus arose from the dead; 1 Cor. 15:20,23 KJB), and is technically upon the first day of the week, but again, was the antitype to the type in Lev. 23:15-22 KJB. This was typically a one time in the year event, and in antitype happened that day, preparing the apostles and disciples for the season of the early rains (Act. 10:47, 19:2-6 KJB).
The text of Rev. 1:10 is said by some that phrase “the Lord’s day” refers to the “first [day] of the week” because some ‘ECF’ said so many years later (supposedly). This is to read into the text, something which does not exist, and to redefine a phrase by non-scriptural means (Isa. 8:20; 1 Pet. 4:11 KJB), and is very dangerous. John the apostle is actually drawing from an OT phrase, found in Isa. 58:13 KJB, which refers to the 7th day the sabbath being called the “[Lord’s] holy day”. The textual structure itself also shows this, and shall be gone into more detail in a bit.
... to be continued ...