Exodus 32:11

And Mosheh was shaken with fear, and began to pray before the Lord his God; and he said, Wherefore should Thy wrath, O Lord, prevail against Thy people whom Thou didst bring up from the land of Mizraim, with great power and with a mighty hand.

ETERNAL, WHY DOTH THY WRATH WAX HOT AGAINST THY PEOPLE? Now when Moses prayed about this great sin, it would have been fitting that he do so by way of confession and supplication, similar to what he said later on, Oh, this people have sinned a great sin, and just as Ezra prayed and confessed because of the faithlessness of them of the captivity,, 9:4. and there is no reason why he should say, why doth the Eternal etc.? Our Rabbis, prompted by this [difficulty], have in various homiletic ways tried to mention several reasons for Moses’ minimizing the sin before Him.
By way of the Truth, [the mystic lore of the Cabala], Moses is saying: “Why do You give permission to the attribute of justice to hold sway over Your people, for You have taken them out of the land of Egypt for the sake of Your Name with the attribute of mercy ruling over them, and with the attribute of justice upon their enemies.”
Now this prayer — Why doth the Eternal… Wherefore should the Egyptians speak — appears really to be the very same prayer he mentioned in the Book of Deuteronomy, And I prayed unto G-d and I said: O Eternal G-d, destroy not Thy people, for the purport of the prayer is alike in both cases, the difference being only that here Scripture mentioned the prayer before it told us that he came down from the mountain, and there Moses mentioned it after it tells us that he came down from the mountain. But Rabbi Abraham ibn Ezra’s opinion is that Moses did not pray for Israel as long as the idol was among them; but only when G-d told him, Let me alone, that I may destroy them,, Verse 14. and he realized that the fate [of the people] was dependent upon him, did he go down the mountain and destroy the calf, and then he returned to pray for forty days, there being no strict chronological order in the narrative of the Torah. But I do not agree with this opinion. For the prayer he recited upon his return to the mountain [after he had cleansed the camp of the idol] is the one which he mentions, Oh, this people have sinned a great sin. And if it is all one prayer which Moses said during the forty days after he returned to the mountain, why does Scripture divide it, mentioning here [in Verses 11-13] part of it, and after he had come down, mentioning the other part [in Verses 31-32]? Rather, these are two separate prayers. Therefore it appears that when G-d told him Let Me alone, that My wrath may wax hot against them, …

בעמך אשר הוצאת. Note that G’d says: עמך, “your people,” instead of עמי, “My people.” He says אשר הוצאת “whom you have taken out from Egypt,” i.e. not “the one whom I have taken out of Egypt.”

למה ה' יחרה אפך בעמך, Moses, does not accept that all the people have become “his” people as implied by G’d having said to him שחת עמך “your people have become corrupted.” Surely, he reasons, not all the people have sinned. Why should G’d be angry at those who did not sin, the ones who are still “G’d’s people?”