Or HaChaim on Exodus 32:21/אור החיים על שמות ל״ב:כ״א

1 מה עשה לך העם הזה? "What did this people do to you?" Moses recognised that the making of a cast idol for others is not one of the commandments for which one has to sacrifice one's life rather than to do so under duress. Compare Maimonides' treatise on the laws of idolatry chapter three in which he rules that a person who commits such a sin is punishable only by 39 lashes. If a person performs such a deed under duress he is not punishable at all. If he had not been forced to do what he did under threat of death he is punishable by 39 lashes even if he had not been warned of the consequences of his deed by witnesses acceptable in Jewish law (Makkot 6). Moses therefore wanted to know the circumstances which caused Aaron to make the calf.

2Aaron replied: אתה ידעת את העם הזה כי בדע הוא, "you know from observing the people that they are bent on doing something corrupt." He added that as far as Moses' assumption that he, Aaron, had made the calf with his own hands was concerned, this was not so. All he had done was to throw the gold into the crucible. The calf emerged totally unassisted. This follows the description in the Tanchuma which we quoted earlier according to which the Egyptian sorcerers Yanus and Yambrus made the calf. Aaron explained that if not for this factor which was beyond his control, there would not have been a sin at all as he had made neither a form nor an image.

3Another meaning of Moses asking: "what have the people done to you?" could be this: "Did they put you under sufficient pressure so that you could legally have agreed to comply?" Moses asked whether Aaron had correctly contrasted the enormity, חטאה גדולה, of the sin involved before deciding that he did not have to make a martyr of himself by agreeing to do whatever he did. Aaron replied by outlining the circumstances of what had transpired.