teshuva

In last week parasha we had description of what to do when one sins, which korbanot to bring, There is an interesting question on Rambam's opinion on t'shuva (repentance). In his book 'Mishne Torah' he writes (link)

If a person transgresses any of the mitzvos of the Torah, be it a positive command or a prohibition, whether intentionally or unintentionally, he is required to confess before G-d when he repents and returns from his sin, as the verse states, “If a man or woman commits any sins against [another] man...they should confess the sin they committed,”1 which refers to a verbal confession. This confession is a positive command from the Torah...

It seems that Rambam counts confession of sins as one of the 613 mitzvot, however, he does not enumerate t'shuva as one of the 613 mitzvoth. This requires explanation. In one of the Rebbes sichot he discusses that there are really 3 possibilities

1. there is no mitzva of t'shuva but if one decides to do one this is the formula, i.e. one has to confess etc. This is compared to the laws of divorce, one is not obligated to divorce but if he decides to do so there are rules of how to do it.
2. mitzvah of t'shuva is one where one accepts (or re-accepts) the yoke of mitzvot. Since this includes all mitzvot it cannot be counted as one of the mitzvot. In a similar way when it is written "and you will follow my rules" this is not a mitzva.
3. it is one and the same mitzva to repent (do t'shuva) and to confess (viduy). As there is no t'shuva without viduy (the simple reading of Rambam) but also there is no viduy without repentance. This is compared to one who dips in mikve while holding a dead sheretz (dead bug which renders the mikva not effective)

It seems that Rambam agrees with explanation #3.