1. As implied by their name, the "Ten Days of Repentance" ("Aseres Yemei
Tshuvah") are set aside for repentance. During these days, every person is
obligated to repent and turn to G-d before the advent of the great and
awesome day, Yom Kippur [as implied by Leviticus 16:30]: "Purify yourselves
before G-d," and [by Isaiah 55:6:] " Seek G-d when he is to be found." The
Sages say that [the latter verse is referring] to the ten days between Rosh
HaShanah and Yom Kippur."
Therefore, during these days, a person must examine his conduct and turn
away from his bad activities. More sincere repentance is required in the
situation where one is unsure whether he sinned or not, than is the case
when one knows that one has in fact sinned. When a person knows that he
has sinned, he will regret his actions more than when he is unsure. For
this reason, the guilt offering for doubtful sins requires a more expensive
animal than a sin offering [for sins that he is certain he committed].
[During these ten days,] one should increase his Torah study, observance of
mitzvos, and gifts to charity, and should reduce one's business
involvement. Rav Moshe Cordovero z"l writes that these days are like Chol
HaMo'ed, and one should therefore perform only such tasks that are
absolutely necessary. In particular, one should pay attention to
relationships with one's fellow man, correcting any wrongs that one might
have performed, because one cannot receive atonement for such sins until
one returns the stolen property or unjust gain and appeases one's
colleague, so that he forgives the wrong.