Deuteronomy 16:4

4 Let no yeast be found in your possession in all your land for seven days. Do not let any of the meat you sacrifice on the evening of the first day remain until morning.

Read Deuteronomy 16:4 Using Other Translations

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.
No leaven shall be seen with you in all your territory for seven days, nor shall any of the flesh that you sacrifice on the evening of the first day remain all night until morning.
Let no yeast be found in any house throughout your land for those seven days. And when you sacrifice the Passover lamb on the evening of the first day, do not let any of the meat remain until the next morning.