I have not succeeded (in deriving the halacha (Jewish religious law)h) by logic alone. (I must, therefore, derive it thus:) It is written here (Exodus) "Veha'avarta," and there (Leviticus) "ya'avor." Just as here, sanctity attaches to it only in the lifetime of its mother, so, there. In that case, why not say: Just as here, (in the instance of the firstling, only) males (are indicated), there, too, (only) males (should be tithed)? It is, therefore, written (Leviticus, Ibid.) "Whatever passes under the staff"—either males or females.