Rif Pesachim 3b {Pesachim 7a continues ... 7b}

HIDE/SHOW IMAGE
3b

{Pesachim 7a continues}
Since it is not a time of prohibition and not a time of destroying, perhaps he will neglect and not nullify it.

And this that they learnt {in a brayta}: If he was sitting in the study hall and recalled that he has chametz in his house, he should nullify it in his heart, whether on Shabbat or Yom Tov. All is well as regards Shabbat, we can find such a case, such as when Shabbat falls on the 14th. But Yom Tov is a question, for it is after prohibition {has commenced}. And we establish it there as a student sitting before his teacher and he recalls that he has dough which is rolled {but not baked} in his house and fears lest it become chametz, he should preempt it and nullify it before it becomes chametz. But after it becomes chametz, he cannot nullify it.

Rav Yehuda said: One who searches {for chametz} needs to bless.
What should he bless?
Rav Papi cited Rava: al biur chametz {"on removal of chametz"}
Rav Papa cited Rava: levaer chametz {"to remove chametz"}

And the halacha is al biur chametz.

{Pesachim 7b}
And a man must bless