|Positive Mitzvah Seventy-Three
We are commanded to make oral confession of the sins we have committed against Hashem (Baruch Hu) after we have repented of them.
This form of confession: "O Hashem, I have sinned, I have committed iniquity, I have transgressed, and I have done thus and thus." One must elaborate and ask forgiveness with all the eloquence at his command.
Transgressions for which one is under obligation to offer one of the offerings specified by Torah, for which Hashem has promised forgiveness to him who offers them, the offering alone without confession is not sufficient, as the Mechilta says, "Since it says, 'he shall confess that wherein he has sinned', we infer that he must confess upon the sin which he has committed, that is, upon the Chataat-offering while it is still alive, not after it has been slaughtered. The verse does not tell us that the individual is to make confession for any [sin] except that of entering the Sanctuary [in a state of uncleanness]."
For this verse, He shall confess that wherein he has sinned, occurs in the Scriptural portion of Vayikra with reference to the defiling of the Sanctuary and its Hallowed Things, and to [transgressions] which are mentioned together with these [i.e. an Oath of Testimony and an Oath of Utterance]. This is why the Mechilta says that we can derive the obligation of making confession from that verse only in the case of one who has defiled the Sanctuary.
Where do we derive its application in the case of violation of any of the other Mitzvot? From the words of Scripture: "Speak to Benei Yisrael, [When a man or woman commits any of the sins against man, acting treacherously against Hashem, and that person is guilty;] they shall confess [their sin which they have done."]
Where do we further [extend the obligation so as to make it apply to those Mitzvot whose transgression entails the penalty of] extinction or death [by the hand of Heaven]? From the words "their sin, that is, all their sins, extending the application [of confession] to Negative Mitzvot. "Which they have done", extends the application to [violations of] the Positive Mitzvot.