Imam Sajjad (a.s) said: “The rights of the tongue include forbidding it from swearing, and vain talk and fostering proper talking and kindness to the people.”
قال علي بن الحسين (عليهما السلام): حق اللسان إلزامه عن الخنا وتعويده الخير، وترك الفضول التي لا فائدة لها، والبر بالناس، وحسن القول فيهم.
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Risālat al-Ḥuqūq #4The right of the tongue is that you consider it too noble for obscenity, accustom it to good, refrain from any meddling in which there is...