Leviticus 23:32

It [shall be] unto you a sabbath of rest
(See Gill on Leviticus 16:31); and this is thought by some ^F17 to be the sabbath spoken of in ( Isaiah 58:13 ) ;

and ye shall afflict your souls; in the ninth [day] of the month at
even;
the fast was to begin at the close of the ninth day, and to continue to the end of the tenth; so Maimonides ^F18: he begins to fast and afflict himself at the evening of the ninth next to the tenth; and so at the going out of it he continues in his affliction a little while of the night of the eleventh, next to the tenth, which is confirmed by what follows:

from even unto even shall ye celebrate your sabbath;
which some understand of the sabbath in general; but it seems to have a particular respect to the sabbath of the day of atonement, which was to last from the evening of the ninth to the evening of the tenth day.