Below is the chapter appertaining to monastic silence from the Regula Monachorum of Columbanus Hibernus.
Saint Columbanus (540 – 23 November 615; Irish: Columbán, meaning “the white dove”) was an Irish missionary notable for founding a number of monasteries on the European continent from circa 590 in the Frankish and Lombard kingdoms, most notably Luxeuil (in present-day France) and Bobbio (Italy), and stands as an exemplar of Irish missionary activity in early mediæval Europe.
He spread among the Franks a Celtic monastic rule and Celtic penitential practices for those repenting of sins, which emphasized private confession to a priest, followed by penances levied by the priest in reparation for the sin. He is also one of the earliest identifiable Hiberno-Latin writers.
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Of Silence (IV)
The rule of silence is decreed to be carefully observed, since it is written: But the nurture of righteousness is silence and peace.’’
And thus, lest one be apprehended as guilty of much talking, it is needful that he keep silence, except for things profitable and necessary, since according to Scripture, in many words sin will not be lacking.’’
Therefore the Saviour says: By thy words thou shalt be justified, and by thy words thou shalt be condemned.’’
Justly will they be damned who would not say just things when they could, but preferred to say with garrulous loquacity what is evil, unjust, irreverent, empty, harmful, dubious, false, provocative, disparaging, base, fanciful, blasphemous, rude, and tortuous. Therefore we must keep silence on these and kindred matters, and speak with care and prudence, lest either disparagements or swollen oppositions should break out in vicious garrulity.