Every word or letter we utter is been written on us in our chart of deeds as Allah (SWT) says in Quran ( Human being does not utter a word but there is a watcher ready by him. (Sura 50, Verse: 18).
We will never like any bad word to be written in our Chart of Deeds which will be given to us in the Day of Judgment. That is why, we must refrain from swear language and any unsuitable word.
Ameerul Mo'mineen Ali (AS) say a person speaking nonsense, he told him: O , you are dictating on your writing angles a letter to your Lord, so, think before talking.