The tongue is a small organ, yet it carries immense power. Islam teaches that speech can either bring a person closer to Allah or lead to their destruction. Guarding one's tongue is a sign of true piety and self-control.
Allah says:
مَّا يَلْفِظُ مِن قَوْلٍ إِلَّا لَدَيْهِ رَقِيبٌ عَتِيدٌ
"Not a word does he utter but that with him is an observer ready [to record it]."
— Surah Qāf (50:18)
The Prophet ﷺ said:
"مَن كَانَ يُؤْمِنُ بِاللَّهِ وَالْيَوْمِ الآخِرِ فَلْيَقُلْ خَيْرًا أَوْ لِيَصْمُتْ"
"Whoever believes in Allah and the Last Day should speak good or remain silent."
— Sahih al-Bukhari (6136)
He ﷺ also said:
"وَهَلْ يَكُبُّ النَّاسَ فِي النَّارِ عَلَىٰ وُجُوهِهِمْ إِلَّا حَصَائِدُ أَلْسِنَتِهِمْ؟"
"Are people thrown into Hell on their faces for anything other than the harvests of their tongues?"
— Sunan al-Tirmidhi (2616)
Abu Bakr (RA) used to hold his tongue and say, "This has led me to many troubles."
Avoiding gossip, lies, backbiting, and foul speech preserves dignity and earns Allah's mercy.