The believer does not curse or speak obscenely

The Messenger of Allah ﷺ said: "The believer is not one who attacks others, nor one who curses, nor one who is obscene, nor one who is foul-mouthed."

قَالَ رَسُولُ اللَّهِ ﷺ: «لَيْسَ الْمُؤْمِنُ بِالطَّعَّانِ، وَلاَ اللَّعَّانِ، وَلاَ الْفَاحِشِ، وَلاَ الْبَذِيءِ».

"Al-Fuhsh is not present in anything but it mars it, and Al-Haya' is not present in anything but it beautifies it."

قَالَ رَسُولُ اللَّهِ ﷺ مَا كَانَ الْفُحْشُ فِي شَيْءٍ إِلاَّ شَانَهُ وَمَا كَانَ الْحَيَاءُ فِي شَيْءٍ إِلاَّ زَانَهُ وَفِي الْبَابِ عَنْ عَائِشَةَ