Mischna zu Schemot 25:1

Five may not give terumah, and if they do so, their terumah is not considered terumah:A heresh (deaf-mute); an imbecile, a minor, And the one who gives terumah from that which is not his own. If a non-Jew gave terumah from that which belongs to an Israelite, even if it was with his permission, his terumah is not terumah.