The phrase is
Nihil Obstat [or
Quominus Imprimatur] (Lat., Nothing hinders [it from being printed]) The words by which the censor of books certifies that he has inspected a given work and finds therein nothing contrary to faith or good morals. You will find this in the beginning of any Bible, Catechism, or other official work approved by the Church to be read by the Christian faithful.