Why did he say "Ki Pesha'ai Ani Yode'a"?
Radak: I know that I sinned; I do not deny it, like Kayin said "Lo Yadati" (Bereishis 4:9).
Malbim: This corresponds to "Kabeseni me'Avoni" (verse 4). The stain is removed from the Nefesh, since it no longer denies the Mitzvah.
What is the meaning of "v'Chatasi Negdi Tamid"?
Rashi: I constantly regret and worry about my sin. It is as if it is always in front of me. Sha'arei Teshuvah (1:48) - it is proper for one who sinned to always remember it and never forget it.
Radak: I constantly regret and am pained over this sin.
Malbim: This corresponds to "ume'Chatasi Tahareni" (verse 4). Since my sin was only against You (verse 6), Teshuvah suffices for Taharah.
