None of you should point a weapon at his brother, for he does not know; perhaps the devil causes his hand to slip, and then he falls into a pit of the Fire

Abu Hurayrah (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "None of you should point a weapon at his brother, for he does not know; perhaps the devil causes his hand to slip, and then he falls into a pit of the Fire."

The Prophet (may Allah's peace and blessings be upon him) warned that a Muslim should not point any type of weapon at his fellow Muslim, as he does not know; perhaps the devil incites him to move the weapon in his hand, thus, will kill or harm his brother. This would result in committing a sin that would cause him to fall into a pit of the Fire.