אך ביום הראשון תשביתו שאור מבתיכם
שמות יב – טו
To remove all chometz from our premises before Pesach.
Males and females.
So we remember the miracles Hashem did for us in Egypt.
In the 1st and 2nd perek of Psachim
If one doesn't do it
He has neglected to perform the positive commandment of תשביתו. In addition he has transgressed the negative commandment of שאור לא ימצא בבתיכם. How ever he does not receive Malkos, because one only receives lashes if he has performed an act of transgression. Here his trangression did not feature an action.