All kinds of animals, birds, reptiles and sea creatures are being tamed and have been tamed by mankind, but no human being can tame the tongue. It is a restless evil, full of deadly poison.
With the tongue we praise our Lord and Father, and with it we curse human beings, who have been made in God’s likeness. Out of the same mouth come praise and cursing. My brothers and sisters, this should not be. Can both fresh water and salt water flow from the same spring? My brothers and sisters, can a fig tree bear olives, or a grapevine bear figs? Neither can a salt spring produce fresh water.
James 3:7-12 (NIV)