What did the Prophet Muhammad (saw) say about refreshing or renewing our knowledge of the sacred books?
 'Abdullah is reported to have said:                      Keep refreshing your knowledge of the sacred books (or always renew your knowledge of these sacred books) and sometimes he would mention the Qur'an for it is more apt to escape from men's minds than animals which are hobbled, and the Messenger of Allah (may peace be upon him) said: None of you should say: I forgot such and such a verse, but he has been made to forget.