Bittul (nullification) and Mechira (sale)

Question

Sorry if this is a duplicate. It is my understanding that one must sell his chometz, prior to declaring his chometz nullified. Reason being, how can one sell something that is null and void? It is also my understanding that the rav sells the chometz in the hour prior to it becoming assur behana - forbidden to benefit from. Must one find out exactly when the rav is selling to ensure he didn’t nullify too soon? This is very applicable for someone who burns his chometz earlier, in theory he should post pone his nullification until the last moment to ensure the rav sold it. Is this correct?

Answer 1

The Ramban Pesachim 4b says that Bittul (nullification) can only work on chametz that he completelely abandons ownership.

ה"מבטלו בליבו" - אין אדם עובר אלא על חמץ שלו שהוא רוצה בקיומו ודעתו עליו, הא נתייאש ממנו ונתן דעתו שאינו רוצה מחמת איסורו, ולא יהנה בו לעולם, אינו עובר
"he annuls it in His heart" - A person is only considered in possession of Chometz (and subsequently transgresses bal yerae on pesach) if he wants its existence and he is thinking about keeping it. Only if he abandons it and says in his mind that he does not want it and will not benefit from it for ever after is he free of its possession.

So chametz that one wants to benefit from through sale to a gentile is automatically not included in this nullification since one does not abandon possession of the chametz as either:
1. Monetary benefit will come out of the sale if the gentile wants his chametz,
2. He will repossess the chametz after Pesach from the gentile and eventually have personal benefit.

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{Note: i think this idea is also illustrated in Nedarim 43b: כל הנודר אין דעתו על מה שהפקיר - one automatically does not forbid something verbally (amount his other possessions) that he had declared owner-less (even though it's still in the owners domain ), so too something which will be owned by someone else via sale (even though it's still in the owners domain ) is automatically not included in the Bittul, which is also a verbal declaration, since he has already set his mind to save that chametz for someone else.}