Halakhah su Geremia 3:27

"Indeed we have sinned". Even though the viddui was composed in accordance with the 'aleph bet' it is said at the beginning "we have sinned" before the rest of the confessions as it says Midrash Tanchuma "the people came before Moses and said 'we have sinned'" because they said "we have sinned" they were forgiven immediately. And it says in another place [Midrash Tanchuma Warsaw ed. Parshat Balak 10] that "anyone who sins and says 'I have sinned' an angel is not permitted to harm them. There are those who interpret 'aval' to mean 'alas' we have sinned and there are those who interpret it as 'indeed we have sinned' (Gen. 42:21). "We and our ancestors" is in the manner of "confessing the sins that we Israelites have committed against You, sins that I and my father’s house have committed." (Nehemiah 1:6) and in the manner of "stood and confessed their sins and the iniquities of their fathers" (Nehemiah 9:2). And it is written "For we have sinned against the LORD our God" (Jeremiah 3:25). [He then goes on to give a citation every word in the Viddui]

One is not considered pious unless he is able to overlook personal grievances. If people come before him who have wronged him and have dealt with him unworthily, and now are sorry and seek his forgiveness; that which is in their power to correct of the wrong which they caused, they correct, and for that which they cannot remedy, they repent and seek his pardon, and agree to accept any judgement he sees fit to pass upon them. And when this one sees that it is in his power to do evil to them and repay them in kind, he forgives them with a whole heart and does not do evil to them. Because of this he is called pious, as it is written, “Return thou backsliding Israel, Saith the Lord; I will not frown upon you for I am merciful” (Jer. 3:12). And so the children of Jacob, when they sinned against Joseph, he forgave and did not repay in kind. And this is the root of Hasiduth, he must do beyond the line of strict justice in all matters, as it is written “and gracious in all his works” (Ps. 145:17).