The Rambam (Rabbi Moshe Maimonides, Spain-Egypt, 1135-1204), in his Hilchot Teshuva (2:1; listen to audio for precise citation), introduces the concept of "Teshuva Gemura," or "complete repentance." He explains that a person achieves "complete repentance" when he encounters the precise same situation in which he had committed a sin, and, despite experiencing the same desire for the sin, he controls his passions and desists. Nevertheless, if a person repents only upon reaching old age, after his passions have subsided, his repentance is accepted, even though he cannot be said to have achieved "complete repentance." In fact, the Rambam emphasizes, even if a person repents only in the final moments before his death, his Teshuva is accepted.
In the next passage, the Rambam presents to us the essential definition of Teshuva, the basic components that the process of repentance entails. He writes that one must "abandon" the sin by eliminating all thoughts of it from his mind and firmly resigning himself to never repeat the act. In addition, the sinner must feel sincere, genuine remorse for having committed the wrongful act, and verbally express these feelings. The Rambam adds, "…and the Knower of mysteries will testify about him that he will never repeat it again." At first glance, the Rambam appears to say that once a sinner performs Teshuva and sincerely regrets his wrongful act, God, who knows future events, can determine that he will never return to his sinful ways. However, the Kesef Mishneh commentary (by Rabbi Yosef Karo, author of the Shulhan Aruch) explains differently, claiming that the sinner must call God as a witness to his resolve never to repeat the sin. So firm must the penitent sinner be in his resolve that he must be able to call God as a witness to the fact that he will never repeat the given offense.
In Halacha 3, the Rambam emphasizes the importance and indispensability of both verbal confession and the internal resolve to change. He writes that if a person verbally confesses his wrongdoing without resolving in his heart to never repeat the sin, he is comparable to a person who immerses in a Mikveh while holding the carcass of a Sheretz (rodent) in his hand. So long as he continues holding the Sheretz, the cause and source of his state of ritual impurity, he can never achieve ritual purity, no matter how many times he immerses in the Mikveh. Similarly, regardless of how many times a person confesses and declares that he has acted wrongly, he does not achieve Teshuva without committing himself to change. Conversely, it does not suffice for a sinner to resolve never to repeat the sin without verbally confessing. The Rambam here cites Moshe's petition to God in the wake of the sin of the golden calf in which he declares, "Please, this nation had committed a grave sin – they made a golden idol" (Shemot 32:31). From this verse we infer that a sinner must verbally confess and specify the particular offense he committed.
Summary: The process of Teshuva includes verbal confession, sincere remorse, and firm resolve never to repeat the given act. A sinner achieves the highest level of repentance when he finds himself in the precise same situation in which he had originally sinned and still feels tempted to commit the offense, but refrains. Nevertheless, even if a person repents only in old age, when he no longer feels driven to repeat the sin, his repentance is nevertheless valid and is accepted by God.
