From the Rule of St. Benedict, Chapter 6
Let us do what the Prophet says: "I said, 'I will guard my ways, that I may not sin with my tongue. I have set a guard to my mouth.' I was mute and was humbled, and kept silence even from good things" (Ps. 38:2-3). Here the Prophet shows that if the spirit of silence ought to lead us at times to refrain even from good speech, so much the more ought the punishment for sin make us avoid evil words.Therefore, since the spirit of silence is so important, permission to speak should rarely be granted even to perfect disciples, even though it be for good, holy edifying conversation; for it is written, "In much speaking you will not escape sin" (Prov. 10:19), and in another place, "Death and life are in the power of the tongue" (Prov. 18:21).For speaking and teaching belong to the mistress; the disciple's part is to be silent and to listen. And for that reason if anything has to be asked of the Superior, it should be asked with all the humility and submission inspired by reverence.But as for coarse jests and idle words or words that move to laughter, these we condemn everywhere with a perpetual ban, and for such conversation we do not permit a disciple to open her mouth.