The Sefer Mitzvos Katan interprets this verse as a commandment to do teshuvah, meaning that a person who has sinned is obligated to repent, and has neglected to fulfill a mitzvah if he does not.
Others, however, read this verse as foretelling that the Jewish people will ultimately repent, but not necessarily as a commandment to do so. Indeed, according to some opinions, repentance is not an obligation of its own; it is only the means (along with the verbal confession) by which a person can atone for his sins if he so desires.
This debate reflects two aspects of teshuvah as explained in the teachings of Chassidus. According to Chassidus, the soul comprises 613 spiritual “limbs” or faculties, each corresponding to a particular mitzvah, and a deficiency in the fulfillment of a mitzvah causes a deficiency in the corresponding limb in one’s soul.
Teshuvah, however, has the ability to repair those “limbs” of the soul that have been damaged. This is because the profound desire to reconnect with G-d draws from the very essence of the soul—the source from which the individual “limbs” of the soul extend. Teshuvah thus draws new life into all the “limbs,” restoring them to their proper “health.”
This explains the opinion that teshuvah is not one of the commandments. Feelings that stem from the depths of your heart, expressing the essence of your soul, must come from within; when you act out of duty, you are not expressing your most natural self. Therefore the Torah does not command you to repent, since only when teshuvah is motivated by your own free choice is it clear that it stems from the purest essence of the soul.
Nevertheless, the prevalent opinion is that teshuvah is in fact a mitzvah, for the goal of teshuvah is not only feelings of regret and a burning desire to return to G-d, but the practical observance of His mitzvos that these feelings will engender in the future. As such, although teshuvah must stem from within and not be motivated by duty alone, it is still a mitzvah like all the others, in order to remind you of its objective—to invigorate your actual fulfillment of the mitzvos, your obligations toward G-d.
—Likkutei Sichos, vol. 38, pp. 18–25
