Abu'l-Qasim (the kunya of Messenger of Allah, may peace be upon him), said: He who pointed a weapon towards his brother the angels invoke curse upon him even if he is his real brother so long as he does not abandon it (the pointing of weapon towards one's brother Muslim). (Using translation from Muslim 2616a)
"إِنَّ الْمَلائِكَةَ لَتَلْعَنُ أحَدَكُم إِذَا أَشَارَ إِلى أَخِيه بحَدِيدَة، وَإِنْ كَانَ أَخاهُ لأَبيهِ، وَأُمِّهِ".