Mukhtasar Bukhari (Abridged) 2107 — Controlling the tongue

Narrated from Sayyiduna Sahl bin Sa'd (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever guarantees me (the proper use of) what is between his jaws and what is between his legs, I guarantee Paradise for him." (i.e., he never misuses these two in the rights of Allah or the rights of people.)