Abdullah bin Amr bin Aas

“Paradise is forbidden for every foulmouthed person.”

Sayings of the Companions, p.22 — Maktaba tul Madina

“There is no limb in a believer's body which is more beloved to Allah Almighty than the tongue; it is due to this very tongue that Allah Almighty will admit him into Paradise. And there is no limb in a disbeliever's body which is more disliked by Allah Almighty than the tongue; it is due to this very tongue that Allah Almighty will cast him into Hell.”

Sayings of the Companions, p.23 — Maktaba tul Madina