What do we learn from "Tzidkas ha'Tzadik Lo Satzilenu?"?
Malbim: Hashem does not look at previous deeds, for good or for bad, only on his current deeds. He is unlike a person, that if a servant always served faithfully and now he sinned, the master pardons him. And conversely, if one always did evil, even if he retracts from his way, it will not help; [his master] guards hatred in his heart, to punish him. Hashem is unlike this. A Tzadik who rebels, his prior virtue will not save him; a Rasha who repents will not stumble in his prior evil. He will be pardoned, as if he never stumbled.
What is the grammatical form of "Chatoso"?
Radak: It is Makor (infinitive) like "Kros Lanu" (Shoftim 8:1), "Ad Yom Melos" (Vayikra 8:33).
The verse said that a Tzadik's prior virtue will not save him when he has Pesha. Why does it add that he will not live in "Chatoso"?
Malbim: Indeed, if a Tzadik sinned b'Shogeg, the Rasha's evil will cause the Tzadik to live; he will be a Tzadik compared to the Rasha 1 . However, if the Rasha repented, he is now more virtuous. The Tzadik will not live due to the Rasha's previous evil.
We find that living near someone more virtuous than himself incriminates him. (PF) Lot feared to be near Avraham, and the widow told Eliyahu that his merit aroused mention of her sin (Rashi Bereishis 19:19, from Pesikta Zutresa there).
