It [shall be] unto you a sabbath of rest,....See Gill on "Le 16:31"; and this is thought by some to be the sabbath spoken of in Isa 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 : 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.
R. Alphes, par. 1. Yom Hacippurim, c. 1. fol. 357. 2. Ut supra, (Maimon. Hilchot Shebitat Asher) c. 1. sect.