(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."