Rashi: I do not know how I will find Nofesh (rest).

Ibn Ezra #1: This is said in astonishment. (Surely I know my Nefesh!)

Ibn Ezra #2: I know no evil for my Nefesh.

Malbim #1: If I will say that I am Tam ¹ , and really, I do not know myself - perhaps I am a Rasha, and He struck me properly - I would justify Hashem according to Elifaz' claim "ha'Enosh me'Eloka Yitzdak."

Malbim #2: Even if I am Tam, I do not know my Nefesh - my purity is not from choice. The nature of man's formation dictates how he will be.

Malbim: Death would be better than such life of shame. Even though he knows that he is a Tzadik ¹ , he will say that he does not know, and [perhaps] he is a Rasha.

Malbim #2: Reward and punishment do not apply to me, for I am forced in my actions.