The scientists of ethics, philosophers, and gnostics have paid an especial attention to the plagues of tongue or in better words, plagues of speech. Their advice - specially for the beginners of the path of insight & perfection - has commonly been deliberate & judicious speaking, taciturnity, and finally silence. In the sacred Mathnavi, attention has been paid to the ethical & moral aspects of silence which we call it pious silence" and "wise silence".In this section of Mathnavi which is the joint point of morals & mysticism, the following subjects have been discussed: being truthful & veracious, considering justice in speech, speaking politely, using well-considered speech, taciturnity, quietness in front of the ignorant, silence before the men of God, and finally silence when & where being confidant(é) is required. Besides these two types of silence, Mawlavi has considered a new type of it, namely "mystical silence". About the "mystical silence" the following matters have been surveyed & discussed: silence of the disciple before the spiritual leader, silence in the mood of perplexity, silence in the mood of love, silence in the mood of zeal, silence where & when keeping divine secrets is required, and finally submission to the will of God and having no complaint.