פּירוש אויף שמות 32:12

והנחם AND REPENT — form another resolution, viz., to do them good,

למה יאמרו הגוים, "Why should the nations be able to say, etc.?" Moses suggested that it would be a public desecration of G'd's name to wipe out the Jewish people whom G'd had referred to in Exodus 4,22 as "My first-born son Israel" less than six months previously? It would appear in retrospect that G'd had orchestrated the Exodus only in order to kill this people in the desert? Once all the nations which served idols realised that serving the one and only G'd led to disaster they would be confirmed in preferring the various deities which they were in the habit of worshiping. They would conclude that the fact that the G'd of the Israelites had not killed them (the Gentiles) for worshiping idols proved that it was an extremely dangerous thing to convert to Judaism and to acknowledge the G'd in Heaven.

למה יאמרו?, Moses asks that the people be spared for the sake of G’d’s great name if not for their own sake. Why should His name become desecrated?

על הרעה INSTEAD OF THE EVIL You have thought to bring upon them.