Midrash su Deuteronomio 16:4

7) Whence do we derive (the same for) the chagigah that comes with the Pesach (on the fourteenth of Nissan)? Because it is written (Devarim 16:4) "And there shall not remain of the flesh that you sacrifice towards evening on the first day until the morning," which teaches us about the chagigah of the fourteenth that it is eaten for two days and one night. I might think (that it is eaten) for one day and one night. It is, therefore, written "until the morning" — the morning of the second day. And how would I satisfy "a chagigah is eaten for two days"? (A different chagigah,) aside from this one. It is, therefore, written (to negate this, the redundant) "And if a vow or a gift."

(Ibid. 19) "In your houses": What is the intent of this? I might take (13:7) "in all of your boundaries," literally (i.e., even if the chametz is not yours); it is, therefore, written "in your houses." Just as your house is your domain, so "your boundaries" (applies only to chametz that is in your domain) — to exclude (from liability) the chametz of a Jew in the domain of a gentile. Even though he can remove it, it is not in his domain. And to exclude the chametz of a gentile in the domain of a Jew, and chametz under debris, where even though it is in his domain it cannot be removed. You say this, but perhaps the intent of the verse is that chametz is forbidden for "seven days" (viz. Ibid.), in the houses, and for all time, in the boundaries. It is, therefore, written (Devarim 16:4) "And chametz shall not be seen unto you in all of your border for seven days."

(Devarim 16:4) "And there shall not be seen unto you leaven in all of your border for seven days":