Do Protestant writers acknowledge the same?

Answer

They do.
NOTE - "IS there no express commandment for observing the first day of the week as Sabbath,
instead of the seventh day?-None whatever. Neither Christ, nor His apostles, nor the first Christians
celebrated the first day of the week instead of the seventh as the Sabbath."-New York Weekly Tribune,
May 24, 1900.
"The Scriptures nowhere call the first day of the week the Sabbath. . . . There is no Scriptural
authority for so doing, nor of course any Scriptural obligation." The Watchman (Baptist).
"The observance of the first instead of the seventh day rests on the testimony of the church, and
the church alone.' -- Hobart Church News, July 2, 1894.
For additional testimonies, see reading on page 146.

With whom did the prophet Isaiah say Christ would make His grave?
What great truth therefore follows?
What will he the reward of those who honor their parents?
If John, therefore, referred to a day of the week, on what day must he have been in the Spirit?
What was the date of Constantine's famous Sunday law?
What does the Apostle Paul say concerning this?
What reason did Paul give for glorying in tribulations?

Questions & Answers are from the book Bible Readings for the Home Circle