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.

What did John declare concerning Him?
By what other title is the Comforter designated?
What final call to come out of Babylon is to go forth?
7. What questions asked by its worshippers indicate the great station to which this beast-power was to attain?
What was the song of Moses?
What has God promised His children when passing through trials and afflictions?
How should we sympathize with others in their sorrows?

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