The Catholic Press of Sydney, Australia, is empatic that Sunday observance is solely of Catholic origin.
"sunday is a Catholic institution, and its claims to observance can be defended only on Catholic principles...From beginning to end of Scripture there is not a single passage that warrants the transfer of weekly public worship from the last day of the week to the first." 8/25/1900.
Duh. It's not the Sabbath, which is Saturday. I have always said that the observance proper to the Sabbath has been transferred to Sunday. But we can't very well make Sunday the Sabbath any more than we can make Thursday Tuesday.
SD