A smooth silken way to hell – Thomas Brooks

In duty, Mary had learned the holy art of living above duty; in the business of acceptance with God, and justification before God, and reconciliation to God, and salvation by God; she knew no duty but Jesus. She was as happy in denying religious self as she was resolute in denying of sinful self.

Duties trusted to will undo you. When trusted to, duties are but a smooth silken way to hell.