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.

Where is the price of Christ's betrayal foretold?
Does faith set aside the law of God?
At His birth, what message did the angel bring to the shepherds abiding in the field?
How many must meet the test of the judgment?
18. Knowing that the unbelieving Jews would still cling to their false ideas respecting the Sabbath, pray?
How, according to Luke, did Christ answer this question?
What part will the angels have in this event?

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