Kommentar zu Bereschit 4:13

גדול עוני מנשוא MY PUNISHMENT IS GREATER THAN I CAN BEAR (literally, my sin is greater than what can be borne) — This is a question: You bear the worlds above and below. and is it impossible for You to bear my sin? (Genesis Rabbah 22:11).

MY SIN IS GREATER THAN I CAN BEAR. This is in the form of a question: “You bear the worlds above and below, and is it impossible for You to bear my sin?” Thus the words of Rashi quoting Bereshith Rabbah.⁴³⁹22:25.
The correct plain interpretation is that it is a confession. Cain said: “It is true that my sin is too great to be forgiven, and Thou art righteous, O Eternal, and upright are Thy judgments⁴⁴⁰Psalms 119:137. even though You have punished me exceedingly. And now behold, Thou hast driven me out this day from the face of the land⁴⁴¹Verse 14. for in being a fugitive and a wanderer unable to stay in one place, behold, I am driven from the land and there is no place where I can find rest. And from Thy face shall I be hid⁴⁴¹Verse 14. whereas I will not be able to stand before You to pray or bring a sacrifice and meal-offering for I was ashamed, yea, even confounded, because I did bear the reproach of my youth.⁴⁴²Jeremiah 31:19. But what shall I do? Whosoever findeth me shall slay me,⁴⁴¹Verse 14. and You in Your manifold loving-kindness did not decree death upon me.” The sense of this is that Cain said before G-d: “Behold, my sin is great, and You have punished me exceedingly, but guard me that I should not be punished more than You have decreed upon me for by being a fugitive and wanderer and unable to build myself a house and fences at any place, the beasts will kill me for your shadow has departed from me.”⁴⁴³See Numbers 14:9 and Ramban there. Thus Cain confessed that man is impotent to save himself by his own strength but only by the watchfulness of the Supreme One upon him.

גדול עוני מנשוא, after Kayin finally realised how G’d in Heaven supervises every detail which goes on down on earth, he was convinced that G’d must know that his sole motivation in doing repentance was to escape punishment. Even this type of repentance was wrung from him only after G’d had pressured him to display penitence. He was embittered, and this is what prompted him to exclaim that the severity of his sin was such there was no hope to obtain forgiveness which would protect him against retribution in kind. The matter is similar to Saul’s failure in killing Agag, King of Amalek. Saul had said to Samuel: “I have sinned,” only after Samuel had insisted that he make a confession of having failed to carry out G’d’s instructions. (Samuel I 15,24) Samuel had had to tell Saul that G’d had despised him as a future leader of the Jewish people before he could prevail on Saul to acknowledge his wrongdoing. (Samuel I 15,24)