Mishneh Torah — Negative Mitzvot מצוות לא תעשה, Chapter 117
The full Hebrew text of Mishneh Torah, Negative Mitzvot, Chapter 117, with English translation by Maimonides (Rambam).
שלא להותיר מבשר הפסח, שנאמר "ולא תותירו ממנו, עד בוקר" (שמות יב,י).
Not to allow the meat of the Paschal sacrifice to remain [overnight], as [Exodus 12:10] states: "Do not leave over any of it until the morning."