The Messenger of Allah ﷺ said, "When a Muslim points a weapon at his Muslim brother, they are both on the brink of Hellfire. If he kills him, they both fall into it together."
أخبرنا محمود بن غيلان قال حدثنا أبو داود عن شعبة قال أخبرني منصور قال سمعت ربعيا يحدث
قال رسول الله ﷺ إذا أشار المسلم على أخيه المسلم بالسلاح فهما على جرف جهنم فإذا قتله خرا جميعا فيها
No references are available.
Bukhari transmitted it in the Book of Tribulations, chapter "If Two Muslims Meet with Their Swords," hadith 7083, as a suspended narration (talīq), and Muslim in the Book of Tribulations, chapter "If Two Muslims Face Each Other with Their Swords," hadith 2888/16, from the hadith of Shubah through this route. It is also found in Kubra, hadith 3581.