Why will "Mechaseh Pesha'av Lo Yatzli'ach"?
Malbim: He engages in covering his sins. His cover will not succeed. His evil will be revealed in the congregation. They will not have mercy on him, for they see that he does not regret his evil, for he tries to hide them from people, even though Hashem knows them.
What is "Modeh v'Ozev"?
Rashi: He admits to his sins and abandons returning to do them again 1 .
Orchos Tzadikim (Sha'ar ha'Anavah DH Harbeh): It is a humble person. Shamayim has mercy on him.
Malbim: He admits to his sins and resolves to abandon his way. This is a sign that he regrets. Therefore, there will be mercy on him.
Ta'anis 16a: If he does not retract, he is like one who holds a Sheretz - all Tevilos in the world will not help. If he let go of it and immersed, it worked.
Here it says that "Mechaseh Pesha'av Lo Yatzli'ach." It says also "Ashrei Nesuy Pesha Kesuy Chata'ah" (Tehilim 32:1)!
Yuma 86b #1: Here discusses a sin known to others; there discusses one that is not known. Sha'arei Teshuvah (1:18) - public sins profane Hashem's name, so he must bewail and mourn over them in front of people, to be Mekadesh Hashem. Even though a Ba'al Teshuvah should not publicize his sins, he must confess them.
Yuma 86b #2: Here discusses sins Bein Adam l'Chavero; there discusses sins Bein Adam la'Makom. Sha'arei Teshuvah (1:18) - this is because a sin Bein Adam l'Chavero has no Kaparah until he returns the theft and requests pardon from the one whom he pained, shamed or spoke Leshon ha'Ra about him.
