And Moses said, “Today you have been ordained for the service of the LORD, each one at the cost of his son and of his brother, so that he might bestow a blessing upon you this day.”
29. For Moses had said, consecrate yourselves today It is obvious that this verse was added exegetically, to give the reason why this unintimidated ardor impelled the Levites manfully to fulfill their charge, viz., because the exhortation of Moses carried them over every obstacle. The verb, “had said,” must be therefore construed in the pluperfect tense. The translation of some, Amongst others, of the Vulgate.
Moses begins with Aaron, not ordering his death like the ringleaders, because there is a world of difference between those who rush headlong into sin and those surprised by infirmity into it. Aaron deserved to be cut off, and would have been, except Moses interceded for him; now he calls him to repentance, showing him he hardened their hearts and strengthened their hands in idolatry.
AI summary
Commenting on Exodus 32:21-29
And it came to pass on the morrow,.... The eighteenth day of Tammuz it was, the same writers say, that Moses implored the mercy of God for Israel. Jarchi on Exo 32:11 says it was on the seventeenth day the tables were broke, on the eighteenth the calf was burnt, and on the nineteenth that Moses went up to intercede for them: that Moses said...