then Moses stood in the entrance of the camp, and said, "Whoever is on the LORD's side--come to me!" And all the sons of Levi gathered themselves together to him.
Exodus 32:26
Surrounding context
32:25 Now when Moses saw that the people were unrestrained (for Aaron had not restrained them, to their shame among their enemies),
32:26 then Moses stood in the entrance of the camp, and said, "Whoever is on the LORD's side--come to me!" And all the sons of Levi gathered themselves together to him.
32:27 And he said to them, "Thus says the LORD God of Israel: "Let every man put his sword on his side, and go in and out from entrance to entrance throughout the camp, and let every man kill his brother, every man his companion, and every man his neighbor."'