Sforno on Deuteronomy 32:5/ספורנו על דברים ל״ב:ה׳

1שחת לו לא בניו מומם דור עקש ופתלתול, however, a twisted and perverse generation He does not view as His true children, such as when they made the golden calf. מומם, their blemish was not due to anything G’d had done Moses recalls that when G’d first told him about the people having become corrupt during his stay on the mountain that they were “your people” (Exodus 32,7), that although Moses, when accepting the conversion of the mixed multitude to Judaism had meant to sanctify the name of G’d, the fact was that instead of becoming a shining example to the world, these people had corrupted what would otherwise have been a kingdom of Priests. They had re-introduced idolatry among these people so recently weaned from it.