But the seventh day is the sabbath of the LORD thy God: Exodus 20:10
“The royal mandate not proving a sufficient substitute for divine
authority, Eusebius, a bishop who sought the favor of princes, and who
was the special friend and flatterer of Constantine, advanced the claim
that Christ had transferred the Sabbath to Sunday. Not a single
testimony of the Scriptures was produced in proof of the new doctrine.
Eusebius himself unwittingly acknowledges its falsity and points to the
real authors of the change. ‘All things’, he says, ‘whatever that it
was duty to do on the Sabbath, these we have transferred to the Lord’s
Day.’"
Robert Cox, “Sabbath Laws and Sabbath Duties”, pg. 538
