Boniface, Saint, Archbishop of Mainz. [Letter to Eadburh, abbess of Minster in Thanet, 716 or 717] in S.Bonifacii et Lulli Epistolae ep.10

[Letter from Saint Boniface, Archbishop of Mainz, to Eadburg/Eadburga, abbess of Minster in Thanet]
In response to her request, Boniface sends Eadburg an account of an otherworld vision. The monk who had the vision had died and come back to life in the monastery of one abbess, and Boniface had heard the story both from another abbess and from the man himself, so he sends Eadburg his transcription of the eyewitness account. The vision includes the sufferings of the damned and joy of the saved, but also an allusion to purgatory, punishment that will eventually be relieved.
Online at Epistolae (See also Bibliographia record).