SHAFAQNA – Imam Ali (AS) said: Coordinate your tongue and heart. The human being must control his/her tongue because truly the rebellious tongue will destroy its owner. Swear to God, I have not seen a righteous person whom the piety has no use for him/her unless, he/she had controlled his/her tongue (in other words; piety is not possible without controlling the tongue) [1].
[1] Nahjul Balaghah, Sermon 176.