From the booklet, The Thoughts of the Cure d'Ars:
On pages 55 & 56: It is God’s will that on Sundays we should occupy ourselves only with what has to do with His service and the salvation of our soul. By doing so, we draw down blessings on our work during the week.
Pages 22 & 23: How mistaken is he who toils on Sunday with an idea that he is making more money or doing more work. Nothing can ever compensate for the injury one does to oneself by breaking the law of God.