Deuteronomy 16:4 "Nor shall any part of the meat which you sacrificed on the first day at evening, remain all night until the morning"

This Negative Mitzvah refers to the portions of meat of the Festive sacrifice (Korban Chagiga), which is an additional holiday sacrifice that is presented on the festivals (see Positive Mitzvah 52).

This sacrifice is brought on the fourteenth of Nissan and it can be eaten for two days, which means until the morning of the sixteenth of Nissan.

We are cautioned not to leave leftover meat after the time limit set in the Torah and all leftover meat must be burnt.