Exodus 34:25

Thou shall not offer the blood of my sacrifice with
leaven
That is, not kill the passover, while there was any leaven in their houses; so the Targum of Jonathan, (See Gill on Exodus 23:18)

neither shall the sacrifice of the feast of passover be left unto
the morning;
neither any of the flesh, nor of the fat of the passover lamb: if any were left, it was to be burnt, see ( Exodus 12:10 ) ( 23:18 ) .