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.

Through whom will Abraham receive the promise of the future inheritance?
What does it mean when used with reference to law?
In connection with what historical event was the old covenant made?
By whose Spirit did the prophets write?
When are the saints to be like Jesus?
What is one good evidence of genuine repentance?
What is the height of the wall?

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