Hawzah News Agency – The merciful prophet of Islam (pbuh) says:
أمسِكْ لِسانَكَ؛ فإنّها صَدَقةٌ تَصَدَّقُ بها على نَفسِكَ.
‘Guard your tongue, for verily this is a charitable act that you perform for your own sake.’
Source: al-Kafi, v. 2, p. 114, no. 7