26 He took up a position at the entrance to the camp and said, "Whoever is on God's side, join me!" All the Levites stepped up. 27 He then told them, "God's orders, the God of Israel: 'Strap on your swords and go to work. Crisscross the camp from one end to the other: Kill brother, friend, neighbor.'" 28 The Levites carried out Moses' orders. Three thousand of the people were killed that day. 29 Moses said, "You confirmed your ordination today - and at great cost, even killing your sons and brothers! And God has blessed you."
Matthew Henry's Commentary on Exodus 32:26-29
Commentary on Exodus 32:21-29
(Read Exodus 32:21-29)
Never did any wise man make a more frivolous and foolish excuse than that of Aaron. We must never be drawn into sin by any thing man can say or do to us; for men can but tempt us to sin, they cannot force us. The approach of Moses turned the dancing into trembling. They were exposed to shame by their sin. The course Moses took to roll away this reproach, was, not by concealing the sin, or putting any false colour upon it, but by punishing it. The Levites were to slay the ringleaders in this wickedness; yet none were executed but those who openly stood forth. Those are marked for ruin who persist in sin: those who in the morning were shouting and dancing, before night were dying. Such sudden changes do the judgments of the Lord sometimes make with sinners that are secure and jovial in their sin.