"Remember to keep holy the sabbath day. Six days you may labor and do all your work, but the seventh day is the sabbath of the LORD, your God. No work may be done then either by you, or your son or daughter, or your male or female slave, or your beast, or by the alien who lives with you.
Exodus 20:8-10
"Sunday is the property of our good God; it is His own day, the Lord's day. He made all the days of the week: He might have kept them all; He has given you six, and has reserved only the seventh for Himself. What right have you to meddle with what does not belong to you? You know very well that stolen goods never bring any profit. Nor will the day that you steal from Our Lord profit you either. I know two very certain ways of becoming poor: they are working on Sunday and taking other people's property."
St. Jean Marie Vianney
in a homily to his congregation