130:1 The Ten Days of Repentance, as the name suggests, are days designated for repentance. Every person is obligated to return in full repentance to G-d in anticipation of Yom Kippur as per Leviticus 16:30, “Purify yourselves before G-d,” and Isaiah 55:6, “Seek G-d when He is to be found.” Our Sages tell us that this refers to the ten days from Rosh Hashana through Yom Kippur. Therefore, during these days, one must examine his conduct and turn away from his negative deeds. A doubtful sin requires more repentance than a definite sin because a person naturally regrets something more when he knows he has sinned than when he is unsure. This is why the guilt offering for doubtful sins cost more than a sin offering, which was for definite sins. During this period, one should increase his Torah study, his performance of mitzvos, and his donations to charity; he should likewise reduce his business activity. Rav Moshe Cordovero wrote that these days should be treated like Chol HaMoed and that we should not do any non-essential work on them. In particular, we must correct any issues between ourselves and our fellow man. For such matters, there is no atonement until one returns any stolen property or unjust profit and makes peace with the aggrieved party so that he will forgive the one who wronged him.
130:2 It is appropriate for a person to act more stringently during the Ten Days of Repentance than he does during the rest of the year since, during this time, we are asking G-d to treat us with extra kindness. One who normally eats kosher bread from non-Jewish bakers should not do so at this time. Rather, he should limit himself to Jewish bread and take upon himself similar stringencies. (In a pinch, if Jewish bread is not readily available, non-Jewish bread is still permitted – Mishnah Brurah 603:1.)