Why does it say "Terem E'eneh Ani Shogeg"?
Rashi: Before I learned Your Mitzvos, I erred in them and sinned. "E'eneh" is an expression of learning in the Beis Midrash, like "Ta'an Leshoni Imrasecha" (172), "Yachres Hashem l'Ish Asher Ya'asenah Er v'Oneh me'Ahalei Yakov" (Mal'achi 2:12) - Er among Chachamim, and Oneh among Talmidim.
Radak: "E'eneh" is submissiveness - "umi'Hamonam Lo Ya'aneh" (Yeshayah 31:4). Before I was humble, and I sinned, I was Shogeg; I did not turn to Your Mitzvos and words. I did not pay attention to remember them.
Malbim: Before I knew all details of the Mitzvos and their reasons, I could easily transgress a Mitzvah without knowledge. I needed to answer and give an excuse 'I was Shogeg. Teach to me!'
Why does he guard Your words now?
Rashi: The Midrash teaches me to avoid Aveirah. This is why I ask You to teach to me "Tuv Ta'am va'Da'as" (66)!
Radak: Now I see that I sinned when I turned my heart from Your words. I was humbled, and I returned to guard Your words and always remember them, lest I be Shogeg.
Malbim: Do not think that now that I know the reasons for Mitzvos, I do them because intellect obligates, and not because Hashem commanded. No - also now, I guard "Imrasecha", because You said so.
