What is the ruling on one who has become accustomed to swearing and vulgar language?

Whoever is accustomed to insulting and cursing people, this action is a transgression (fusuq) and contrary to the perfection of faith, for the Prophet, peace and blessings be upon him, said: "Insulting a Muslim is a transgression (fusuq), and fighting him is disbelief (kufr)," and "The believer is not a slanderer, nor a curser, nor obscene, nor foul-mouthed." This behavior exposes its perpetrator to Allah's hatred, for he, peace and blessings be upon him, said: "Indeed, Allah detests the obscene and foul-mouthed," and "Indeed, Allah does not love the obscene and vulgar." The true Muslim is he "from whose tongue and hand the Muslims are safe." The Muslim must repent to Allah from this behavior which distances him from his Lord and makes him detestable to people. Mu'adh asked the Prophet, peace and blessings be upon him, about the essence of deeds that bring one closer to Paradise and distance one from Hellfire, so the Prophet took hold of his tongue and said: "Restrain this," then he said: "And are people cast into the Fire on their faces, or on their nostrils, except for the harvests of their tongues?"