Regula Benedicti: good works 11 (chapter IV)
The Latin:
51. et seniori spiritali patefacere,
52. os suum a malo vel pravo eloquio custodire,
53. multum loqui non amare,
54. verba vana aut risui apta non loqui,
55. risum multum aut excussum non amare.
The English:
51. And to disclose them to our spiritual father.
52. To guard one’s tongue against bad and wicked speech.
53. Not to love much speaking.
54. Not to speak useless words and such as provoke laughter.
55. Not to love much or boisterous laughter.