Tongue.

Some people might say that I don't talk much, which might surprise those who think I talk a lot. Truth is, I choose to only speak about certain things to certain people. I only speak if you want to listen. I don't speak if I think it might bring about conflict or misunderstanding. But it doesn't mean that if I'm silent, that I do not have an opinion, that I do not care, hurt or feel. I will only voice it if and when it is necessary to do so. I love words but I value silence, for in silence I can hear even more.

“Rabbish rahli sadri wa yasirli amri wa ahlul uqdatum mil lisani yafqahu qauli”, which translates to: “O God open my chest, make my task easy for me and untie the knot in my tongue so that they may understand me”.

Musa (as) made this Dua before going to Fir'aun, and it can be found in Surah Ta-Ha (verse 25-28).