“Moses saw that the people were running wild. Aaron had let them run wild, to the derision of their enemies. Then Moses stood in the gate of the camp, and said, ‘Who is on Yahweh’s side? Come to me!’ All the sons of Levi gathered around him. He said to them, ‘Thus says Yahweh, the God of Israel. Put your sword on your side, each of you! Go back and forth from gate to gate throughout the camp, and each of you kill your brother, your friend, and your neighbor.’ The sons of Levi did as Moses commanded. About three thousand of the people fell on that day. Moses said, ‘Today you have ordained yourself for the service of Yahweh. Each one of you, at the cost of a son and of a brother, has brought a blessing on yourselves this day.’”
Moses saw that the people were running wild because Aaron let them. He wanted to know who was on Yahweh’s side. The sons of Levi gathered around him. Remember Levi had been the violent one. This time Moses said to put your swords on your side and then kill your brother, your friend, and your neighbor. Then the massacre began, as 3,000 people died that day. This is the first self inflicted wound on the Israelites. Moses, on the other hand told the Levites that they had been ordained for the service of Yahweh by the killing. Thus after Yahweh killed all the first-born Egyptian children and the Egyptian soldiers he encouraged the killing of 3,000 of his own people.