'A still tongue makes a wise head', says one proverb. It has also been said: 'The wounds of a sword may heal one day; the wounds of the tongue, they never may.' And then there is this note of caution: 'Speak when you're angry and you'll make the best speech you'll ever regret.'
While it is true that great good can come from the tongue, it is also true that the tongue can stir up immense enmity and strife. The tongue, despite it being a small organ of the body, has an influence wholly disproportionate to its size. How many conflicts, divisions, divorces and distresses have been triggered by angry words and unbridled tongues! Unfortunately, the tongue as a source of evil is something that our communicative and social-networking culture seldom considers. In contrast to the modern urge to endlessly yap, yell and yodel, our ancients recognized that when a carpet of silence is laid, wisdom begins to settle.
As part of his celebrated and encyclopedic anthology of transmitted prayers from the Prophet , al-Adhkar, imām al-Nawawi (d.676H/1277CE) devotes a separate chapter on the obligation to guard the tongue and the merits of silence. The following is a translation of the opening segments of that discussion:
'Know that it is required of every legally responsible person (mukallaf) that they guard their tongue from all types of speech, save that which contains an overriding benefit. Whenever speaking or keeping silent are equal in their benefits, then the sunnah is to refrain from speaking. For speech that starts off as permissible can quickly degenerate into what is forbidden or disliked. In fact, this occurs a lot, or is more often the habit; and there is no substitute for safety.
It is related in the Ṣaḥīḥs of al-Bukhāri [no.2018] and Muslim [no.47]; on the authority of Abu Hurayrah, may God be pleased with him; who relates that the Prophet , declared: 'Whoever believes in God and the Last Day, let him speak well or keep quiet.'
I say: The soundness of this ḥadīth is agreed upon and contains an explicit stipulation that one must not speak unless one's words are good and that the benefit in doing so is clear and preponderant. Whenever there is uncertainty about the benefit being preponderant or not, one remains silent. Imām Al-Shāfi'i, may God have mercy upon him, has said: “When one intends to speak, let him think before he does so. If there is an overriding benefit, let him speak; but if in doubt, let him desist from speaking until the benefit is clear.”'
Al-Nawawi, al-Adhkar (Jeddah: Dar al-Minhaj, 2008), 535.