"The Messenger of Allah [SAW] said: 'If a Muslim points a weapon at his fellow Muslim, then they are on the brink of Hell, and if he kills him, then they will both fall into it.'" (Using translation from Nasāʾī 4116)
"إِذَا أشَارَ المُسْلِمُ إلى أخيه المُسْلِم بالسِّلاح فهما على حَرْفِ جَهَنَّم، فإذا قتله خرَّا جميعًا فِيه".