"Whoever believes in Allah and the Last Day, let him speak good or remain silent."
Narrated from Abū Hurayrah. Ṣaḥīḥ al-Bukhārī 6018 (Kitāb al-Adab); also Ṣaḥīḥ Muslim (muttafaq ʿalayh).
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In The Tongue
Begin with the rule, for the rule is complete.
Two roads, and there is no permitted middle country of mildly negative but basically harmless. Good, or quiet. Most of what we say about absent men is neither.
Ibn al-Mubārak was asked about the old saying that if speech is silver then silence is gold, and his answer is worth more than the proverb:
Qur'anic Arabic is reproduced in the Uthmani script. Hadith Arabic is reproduced from the published collections named above. The English is a rendering informed by widely used translations, offered as an aid to meaning and not a substitute for the Arabic. Verify what is cited, and consult people of knowledge on anything affecting practice.