Exodus 32:26-28

²⁶then Moses stood in the gate of the camp, and said, “Whoever is for the Lord, come to me!” And all the sons of Levi gathered together to him. ²⁷He said to them, “Thus says the Lord, the God of Israel, ‘Every man of you put his sword upon his thigh, and go back and forth from gate to gate in the camp, and kill every man his brother, and every man his friend, and every man his neighbor.’” ²⁸So the sons of Levi did as Moses instructed, and about three thousand men of the people fell that day.