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.