Exodus 32:25-29

25When Moses saw that the people were unrestrained, because Aaron had let them run wild, to become a joke among their enemies,

26Moses stood at the gate of the camp and said, “Whoever is on Adonai’s side, let him come to me.” Then all the sons of Levi gathered themselves together to him.

27He said to them, “This is what Adonai, the God of Israel says, ‘Every man put on his sword, and go to and fro, from gate to gate throughout the camp, and slay his brother, his friend, and his neighbor.’”

28So the sons of Levi did as Moses said, and that day from among the people there fell about 3,000 men.

29Then Moses said, “Consecrate your hands today to Adonai so that He may give you a blessing today, for every man has been against his son and his brother.”