Anselm, Saint, Archbishop of Canterbury. [Letter to Gunhilda, royal nun, 1093-4] in Sancti Anselmi Cantuariensis Archiepiscopi Opera Omnia 4.43-46

[Letter from Saint Anselm, archbishop of Canterbury, to Gunhilda/Gunnilda, royal nun]
Archbishop Anselm writes to persuade Gunhilda to return to monastic life, reminding her that she is married to God, that she had made vows even if she had not yet been consecrated, that neither God nor the church will forgive her if she does not renounce the world and repent her sin.
Online at Epistolae (See also Bibliographia record).