“However, on the tenth day of the month… and you shall afflict your souls!” (Vayikra 23:24-27)
It is a positive commandment to fast on the tenth day of Tishrei, which is called the day of atonement, as it says “However, on the tenth day of the month… and you shall afflict your souls!”. Chazal explained that the affliction referred to here, means refraining from eating and drinking. They also received a transmission that other bodily enjoyments are also forbidden. These are washing, anointing oneself, wearing leather shoes and cohabitation.
Amongst the roots of this commandment are that one of the many kindnesses that Hashem did for His creations was to fix one day in the year when, together with repentance, the day would atone for the sins. We are therefore commanded to fast on this day. For the enjoyments of the body encourage the physical aspects of the body to be drawn after their inclinations and to sin. These aspects of the body would overcome the wise soul’s inclination to search for the truth which consists of the service of Hashem and all of His messages. It is unfitting that on the day of atonement a person should come to stand for judgement before his Master with a soul which has been dulled and darkened through food and drink, and with the base thoughts of the physical aspect of the body which the soul inhabits, as a person is judged according to the level which he is at at that time. It is therefore good for the person to strengthen the wise soul and to subjugate the physical matter on this respected day, so that it will be fitting and correct to be able to receive its atonement, and the inclinations will not hinder it.
This commandment applies in all places and at times, both to men and to women.