the Day of Atonement: Observed As a Sabbath
Source: TTT
Leviticus 23:28, 32
On this day you are not to do any work, for it is the Day of Atonement, when atonement is made for you before the LORD your God. / It will be a Sabbath of complete rest for you, and you shall humble yourselves. From the evening of the ninth day of the month until the following evening you are to keep your Sabbath.”