Babylonian Talmud, Brachot 32a - 2

And the Lord spoke to Moses, Hurry down, for your people. (Exodus 32:7) What is meant by 'Hurry down, for your people'? R. Eleazar said: The Holy One, blessed be God, said to Moses: Moses, descend from your greatness. Have I at all given to you greatness save for the sake of Israel? And now Israel have sinned; then why do I want you? Straightway Moses became powerless and he had no strength to speak. When, however, [God] said, Let Me alone that I may destroy them, Moses said to himself: This depends upon me, and straightway he stood up and prayed vigorously and begged for mercy. It was like the case of a king who became angry with his son and began beating him severely. His friend was sitting before him but was afraid to say a word until the king said, Were it not for my friend here who is sitting before me I would kill you. He said to himself, This depends on me, and immediately he stood up and rescued him. Now, let Me be, that My anger may blaze forth against them and that I may destroy them, and make of you a great nation. (Exodus 32:10) R. Abbahu said: Were it not explicitly written, it would be impossible to say such a thing: this teaches that Moses took hold of the Holy One, blessed be God, like a man who seizes his fellow by his garment and said before God: Sovereign of the Universe, I will not let You go until You forgive and pardon them. [Soncino translation. Edited for clarity and gender equality]