This excerpt is taken from Sheikh Abu Hamza Abdul Khaliq Siddiqi's book Sahih Fazail Amaal.
عن أبى موسى رضى الله عنه قال: قلت: يا رسول الله! أى المسلمين أفضل؟ قال: من سلم المسلمون من لسانه ويده .
Sayyiduna Abu Musa رضي الله عنه narrates that I asked, O Messenger of Allah! Which Muslim is the best? You صلى الله عليه وآله وسلم said: "The one from whose tongue and hand other Muslims are safe."
Reference: Sahih Bukhari, Book of Faith, Chapter: Which Islam is best? No: 11. Sahih Muslim, Chapter: Explanation of the superiority of Islam, No: 42.
عن سهل بن سعد عن رسول الله صلى الله عليه وسلم : من يضمن لي ما بين لحييه وما بين رجليه أضمن له الجنة .
Sayyiduna Sahl bin Sa’d رضي الله عنه narrates that the Messenger of Allah صلى الله عليه وآله وسلم said: "Whoever guarantees me the protection of what is between his two jaws (tongue) and what is between his two legs (private parts), I guarantee him Paradise."
Reference: Sahih Bukhari, Book of Softening the Hearts, Chapter: Guarding the Tongue, No: 6474.
Sayyiduna Abu Shuraih رضي الله عنه says that I heard the Messenger of Allah صلى الله عليه وآله وسلم say:
من كان يؤمن بالله واليوم الآخر، فليقل خيرا، أو ليصمت
"Whoever believes in Allah and the Last Day, let him speak good or remain silent."
Reference: Sahih Bukhari, Book of Softening the Hearts, No: 6476. Sahih Muslim, Book of Lost Property, Chapter: Hospitality and the like, No: 48.
Sayyiduna Abu Hurairah رضي الله عنه narrates that the Noble Prophet صلى الله عليه وآله وسلم said:
إن العبد ليتكلم بالكلمة من رضوان الله لا يلقي لها بالا يرفع الله بها درجات، وإن العبد ليتكلم بالكلمة من سخط الله لا يلقي لها بالا يهوي بها فى جهنم .
"A man, heedless of the consequences, utters a word pleasing to Allah, and Allah raises his ranks because of it. Likewise, a man, heedless of the consequences, utters a word displeasing to Allah, and because of that one word, he falls into Hell."
Reference: Sahih Bukhari, Book of Softening the Hearts, Chapter: Guarding the Tongue, No: 6478.
Imam Yunus bin Ubaidullah رحمه الله says: "When two things of a servant are correct, then everything else automatically becomes correct. One is his prayer, and the other is his tongue."
Reference: Siyar A’lam al-Nubala: 6/293.
Imam Awza’i رحمه الله says: "Indeed, a believer is of few words and much action, while a hypocrite is of many words and little action."
Reference: Siyar A’lam al-Nubala: 7/125.
