אשר במעלם אבתם עון ואת עונם את והתודו" אלך אני אף :בקרי עמי הלכו אשר ואף בי מעלו יכנע אז או איביהם בארץ אתם והבאתי בקרי עמם (מא-מ כו) "עונם את ירצו ואז הערך לבבם
If "they did viduy for their sins" why would Hashem go with them "bakeri"?
The Kli Yakar explains that from the fact that it doesn’t say "והתודו את עונם והתודו את" but rather "ומעלם אשר מעלו עונם...במעלם" it appears that despite their viduy and the recognition that they were punished because of their sins, they still were unfaithful and they do not do complete teshuvah and leave the sin. Therefore, their viduy is not accepted. As the Rambam rules (Teshuvah 2 3): "Anyone who is misvadeh, says viduy with words but did not resolve in his heart to leave the sin, is like one who immerses with an insect in his hand, that the immersion is not beneficial to him until he tosses away the insect, as it says (Mishlei 28:13) ‘Umodeh v’ozev yerucham, he who confesses and abandons [them] will obtain mercy.’"
The Pardes Yosef adds that viduy that is just lip service is not only ineffective, it is also a sin, and we repent for it on Yom Kippur as we say : "Al cheit shechatanu...beviduy peh" – with viduy said only with the mouth, without charaitah – regret- and azivas hacheit – abandoning the sin.
Harav Azariah Figu, author of Gidulei Terumah, explained this differently: The ikkar of teshuvah is that the sinner should recognize the magnitude of his sin, and should not try to make light of its severity and attribute it to some other reason. When a person completely absolves himself of the sin and blames others for them, his charatah is not sincere, and the teshuvah is not complete and is not accepted. Here as well it says: "Vehisvadu es avonam v’es avon avosam," that in their viduy they attribute the reason for their sins to their forebears who caused them to sink into sinning, and therefore, it is not accepted.
Harav Yosef Shaul Nathanson of Lvov explained this according to the ruling of the Rambam (ibid 7 3) that it is not enough for the sinner to regret the sins that he actually committed, and he must also "introspect into the bad opinions that he has and repent from the anger and the enmity and jealousy and the mockery as these sins are worse than the ones that he actually committed." Here, the misvadim only regretted the sins that "they committed against Me" – in action, without expressing regret for the sins of their heart, and therefore, their viduy is not accepted.
Harav Yissachar Dov of Belz explained that the viduy needs to be said with submission and a broken heart, and here, the passuk implies that the viduy was said with impudence: "Vehisvadu...bema’alam asher ma’alu Bi," with the same impudence that they had when the sinned against Me, and therefore, it was not accepted.
Kli Yakar; Bina L’Itim Drush 7; Divrei Shaul, Third Edition; Kovetz Ohr Hatzafun 131 p. 19 Vayeira 5764; Pardes Yosef
