Book 4 of 4 - External Means by which God Invites Us into the Society of Christ and Holds Us Therein
Chapter 13 - Rash vows and their entanglements
20-21 - Unlawful and superstitious vows are not binding
20. Monastic vows are not binding. If God forbids taking them, He also forbids continuing in them. "If men have undertaken anything rashly through the fault of ignorance, why should they not desist from it when once freed of error?"
21. If God abrogates what man confirms, there is no bond to keep the vow. The cross removes the obligation to the law - Gal 3:13 - how much more does it release us from monastic vows?