Leviticus 16:29 - The Popular Commentary by Paul E. Kretzmann

And this shall be a statute forever unto you: that in the seventh month, on the tenth day of the month, ye shall afflict your souls, bowed down in penitence and humiliation, and do no work at all, whether it be one of your own country, or a stranger that sojourneth among you. The tenth day of the first month of the civil year, known first as Ethanim, and afterwards as Tishri, although not included in the great festivals, was yet of such importance as to give it the name of being the most solemn day in the year, and it was often designated simply as "the day. "