Why does it say "Lema'an Shimcha"?
Rashi: Due to Your name, which is great, pardon my great sin. It is proper for the great to pardon a great sin!
Radak: Your name is called Tov v'Salach.
Malbim: You will pardon even the Avon (refer to 25:11:3:4 and the note there) due to Your name, for You are full of mercy and pardon sins.
What is "Avoni"?
Radak: It is the special sin greater than all those that he did - that of Bas Sheva.
Why did he say "Ki Rav Hu"?
Rashi: Refer to 25:11:1:1.
Radak: Even though I requested pardon for all my sins, for that one I repeat to request, for it is great.
Sha'arei Teshuvah (4:22): With His great Chesed, He pardons even those who rebel against Him, when they repent with all their hearts.
Malbim: He asked Hashem not to remember "Chat'os Ne'urai u'Fesha'ai" (verse 7). He additionally asks that He totally pardon the sin, even the Avon, which is more severe than Pesha 1 .
Yuma 36b: The Halachah follows Chachamim, who say that Pesha (rebellion) is worse than Avon. And even R. Meir, who says to confess 'Avisi, Pashati, Chatasi', could agree that Pesha is worse! (PF)
