[The following] five [individuals] should not separate terumah; if they did separate te-rumah, their terumah is not terumah: a deaf person, a deranged person, a minor, and one who separates terumah from that which is not his. [If] a non-Jew separates terumah from [the produce] of a Jew, even with [the Jew's] consent, his terumah is not terumah.