Sforno on Leviticus 22:29/ספורנו על ויקרא כ״ב:כ״ט

1לרצונכם תזבחו ביום ההוא יאכל, your intentions at the time of performing the sacrificial procedure must be to eat it on the same day, (compare Rashi), the reason for these rules bein אני ה', seeing that I am perfect and My work is perfect, I will not tolerate deviations by you either by shortening the period or lengthening it. [seeing that this legislation has been dealt with in the Torah already in Leviticus 7,15-17 may have prompted the author to refer to Rashi’s explanation on our verse that the beginning of the time frame is meant, i.e. the same day, one must not wait until the second day to start eating from it.. Ed.]