Exodus 23:18

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

No meat offering, which ye shall bring unto the LORD, shall be made with leaven: for ye shall burn no leaven, nor any honey, in any offering of the LORD made by fire.

And there shall be no leavened bread seen with thee in all thy coast seven days; neither shall there any thing of the flesh, which thou sacrificedst the first day at even, remain all night until the morning.

And ye shall let nothing of it remain until the morning; and that which remaineth of it until the morning ye shall burn with fire.

And they shall eat the flesh in that night, roast with fire, and unleavened bread; and with bitter herbs they shall eat it.

And the flesh of the sacrifice of his peace offerings for thanksgiving shall be eaten the same day that it is offered; he shall not leave any of it until the morning.

If he offer it for a thanksgiving, then he shall offer with the sacrifice of thanksgiving unleavened cakes mingled with oil, and unleavened wafers anointed with oil, and cakes mingled with oil, of fine flour, fried.

Seven days shall ye eat unleavened bread; even the first day ye shall put away leaven out of your houses: for whosoever eateth leavened bread from the first day until the seventh day, that soul shall be cut off from Israel.