Exodus 32:27 - Joseph Benson’s Commentary on the Old and New Testaments

Thus saith the Lord God of Israel What Moses now did was not done merely in the heat of a pious zeal, but by a divine influence and direction; and therefore can be no warrant to others to imitate his example, who cannot pretend to the same authority, and who are placed in circumstances entirely different from those in which he and the Israelites were placed. Slay every man his brother, and every man his companion Moses being, under God, their chief ruler, at God's command, passed this extraordinary sentence upon the offenders, without the common process in courts of judicature, requiring the sons of Levi to go armed into the camp, and cut off the most notorious and obstinate offenders, without regard to kindred, friendship, or any other distinction whatever. And there was no fear of their killing the innocent in this case, because Moses had called to himself all that were on God's side. These, either by resorting to him, or by retiring to their tents, were separated from the guilty, who were impudently walking about in the camp, trusting to their numbers. It may be observed further here, that, besides the authority of the command of Moses to the Levites, a peculiar impulse from God must have actuated them in this business, otherwise it is very improbable that they should have obeyed so readily, or have dared to attack so many; and a peculiar consciousness of guilt and terror must have fallen on the people, to have caused such a multitude to submit to be slain without making any resistance.