But the seventh day is the sabbath of the LORD thy God:....For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it.
Exodus 20:10,11
“We
frankly say ‘yes’, the Church made this (Sunday) change, 
made this law
as she has made many other laws… It is always somewhat laughable to see
the Protestant churches, in pulpit and legislature, demand the
observance of Sundays of which there is nothing in the Bible. …that
Protestants, who accept the Bible as the only rule of faith, should by
all means go back to the observance of the Sabbath… The fact that they
do not, stultifies them in the eyes of every thinking man!”
Pope Pius XII – 1951