"Tashbisu se'or m'bateichem... ki kol ochel chametz v'nichresa hanefesh ha'hi m'yisrael m'yom harishon ad yom hashevi'i. U'bayom harishon mikra kodesh..." (Shmos 12:15-16).
The pasuk is grammatically difficult, as the phrase "m'yom harishon ad yom hashevi'I" does not modify its antecedent clause "v'nichrisa..." (using words like antecedent clause is what happens when your wife has a phd in English). The Netziv quotes a chiddush from R' Betzalel Cohen, the dayan of Vilna, who explains that it refers back to the mitzva of "tashbisu" which opened the pasuk. Although tashbisu begins of erev Yom Tov (see Rashi), the mitzva continues throughout Yom Tov obligating one to destroy any chameitz found. On that basis the Netziv is mechadesh that if chametz is found on Yom Tov, according to those Rishonim who hold it may be burned if you have not done bittul before Yom Tov (daf yomi learners - see rashi in peaschim 6) the reason is not because of mitoch (since burning is allowed for ochel nefesh it is also allowed to destroy chametz), but because the aseh of tashbisu combined with the lav of owning chametz is enough to be doche the ashe and lav of Yom Tov!