'Penitence' in the Bible

“This shall be a permanent statute for you: in the seventh month (nearly October) on the tenth day of the month you shall humble yourselves [by fasting] and not do any work, whether the native-born or the stranger who lives temporarily among you;

It is a Sabbath of solemn rest for you, and you shall humble yourselves; it is a permanent statute.

“Also the tenth day of this seventh month is the Day of Atonement; it shall be a holy convocation for you, and you shall humble yourselves [by fasting] and present an offering by fire to the Lord.

If there is any person who will not humble himself on this same day, he shall be cut off from his people [excluding him from the atonement made for them].

It is to be to you a Sabbath of complete rest, and you shall humble yourselves. On the ninth day of the month at evening, from evening to evening you shall keep your Sabbath.”