Here are two interesting quotes concerning the Sabbath.
…It was not, however, without a reason that the early Christians substituted what we call the Lord’s day for the Sabbath. The resurrection of our Lord being the end and accomplishment of that true rest which the ancient Sabbath signified, this day, by which types were abolished, serves to warn Christians against adhering to a shadowy ceremony. I do not cling to the number seven as to bring the Church under bondage to it, nor do I condemn churches for holding their meetings on other solemn days, provided they guard against superstition.”
“If anywhere the day is made holy for the mere day’s sake—if anywhere anyone sets up its observance on a Jewish foundation, then I order you to work on it, to ride on it, to dance on it, to feast on it, to do anything that shall remove this encroachment on Christian liberty.”