Musar su Levitico 19:6

והנותר ממנו באש תשרופו . Concerning the requirement to burn left-over portions of the sacrifices that have not been consumed within the time frame given by the Torah (19,6), he writes that since these meat portions have become the property of a higher domain and it is in the nature of meat to deteriorate, which would be an affront to Heaven, it is better to burn it. Since Heaven has appointed a separate angel for each day who is concerned with these offerings, etc., it would not do to leave over something from the domain of one angel to that of another on the following day. Were we to do that, it would appear as if tomorrow's angel would be invited to partake only of left-overs. Considerations such as these may account for the Halachah stipulating that one may not prepare foods from one day of a festival for the succeeding day.