Exodus 34:25

לא תשחט וגו׳ THOU SHALT NOT OFFER [THE BLOOD OF MY SACRIFICE TOGETHER WITH LEAVEN] — i. e. thou shalt not kill the Passover lamb whilst leaven is still existent in your possession. This is an admonition addressed to him who slaughters the Passover lamb, as well as to him who sprinkles its blood or to one of the members of the party formed to eat that lamb in company (Pesachim 63a). ולא ילין NEITHER SHALL [THE SACRIFICE OF THE FESTIVAL OF PASSOVER] REMAIN OVER NIGHT — Understand this as the Targum renders it: ולא יביתון ... בר ממדבחא … ‎“There shall not remain overnight away from the altar till the morning the fat of the sacrifice” — this law of leaving the fat away from the altar overnight does not serve to invaliditate the sacrifice if it has been placed on the top of the altar some time during the night, even if it be not entirely burnt by morning, nor is the law about leaving the fat overnight infringed except if it has not been placed on the altar by the dawn of the morning (but any time during the night one may lift it up from the pavement on to the altar (Zevachim 87a; cf. Rashi on Exodus 23:18). זבח חג הפסח means the pieces of its fat (which had to be burnt on the altar). From here you may derive the law concerning all cases of burning the pieces of fat and the limbs of sacrifices (i. e. you may derive the general rule regarding all sacrifices).

לֹֽא־תִשְׁחַ֥ט עַל־חָמֵ֖ץ דַּם־זִבְחִ֑י וְלֹא־יָלִ֣ין לַבֹּ֔קֶר זֶ֖בַח חַ֥ג הַפָּֽסַח׃

Thou shalt not offer the blood of my sacrifice with leaven; neither shall the sacrifice of the feast of the passover be left to the morning.