Adam Clarke on Exodus 32:33

Whosoever hath sinned against me, him will I blot out - As if the Divine Being had said: "All my conduct is regulated by infinite justice and righteousness: in no case shall the innocent ever suffer for the guilty. That no man may transgress through ignorance, I have given you my law, and thus published my covenant; the people themselves have acknowledged its justice and equity, and have voluntarily ratified it. He then that sins against me, (for sin is the transgression of the law, 1Jn 3:4, and the law must be published and known that it may be binding), him will I blot out of my book." And is it not remarkable that to these conditions of the covenant God strictly adhered, so that not one soul of these transgressors ever entered into the promised rest! Here was justice. And yet, though they deserved death, they were spared! Here was mercy. Thus, as far as justice would permit, mercy extended; and as far as mercy would permit, justice proceeded. Behold, O reader, the Goodness and Severity of God! Mercy saves all that Justice can spare; and Justice destroys all that Mercy should not save.