Excellent cross reference Bob Ryan, I even copied the places you mentioned for my own reference concerning Sabbath.
I am also presenting another proof of the importance of the Sabbath in our lives, as the evidence that the Sabbath remains very important Day to observe for whole humanity, as a statute given from GOD and not from men.
Paul presented words of GOD about Sabbath Day not only as a Day of rest, but also as a Day of Salvation, and as a place of His habitation.
Hebrews 4.4-5.9-10
4.He has thus said somewhere concerning the Seventh Day, "And GOD rested on the Seventh Day from all His works" (Genesis 2.2),
5.and again in this passage, "They shall not enter My rest." (Psalm 95.11)
9.There remains a Sabbath rest for the people of GOD.
10.The one who has entered His rest, has himself also rested from his works, as GOD did from His.
In verses above Paul compared the Sabbath rest of GOD with His everlasting Kingdom, and us as those who labor in our physical world in order to achieve our eternal spiritual rest, which means our everlasting Sabbath! (everlasting life)
According to the verses presented by Bob Ryan, Apostles of Christ never violated Sabbath, and all first Christians always congregated on the Sabbath and observed this Day religiously, until some corrupt people changed it to a Sunday worship, which against the rule of GOD, because no commandments ever been issued by GOD Father to discard Sabbath, nor by Jesus Christ or His Apostles.
And because the word of GOD always prevails against the word of the mortals, Sabbath still remains the Day which must to be observed, and on such Day the worship of GOD must be conducted.
Above all, Jesus Himself never violated the Sabbath Day, and never changed or rejected it in any way, and so, Sabbath still remains as the Day to observed, and according to the verse that Bob Ryan presented Isaiah 66.23, Sabbath will remain as such forever for all times and for all generations to come.
Isaiah 66.23
23.And it shall be from new moon to new moon, and from Sabbath to Sabbath, all mankind will come to bow down before Me, says the Lord.
Amen.