Before the incident of Ohud, the problem of the hypocrites did not seem as important as it really was. After the battle, Muslims knew that they had snakes in their sleeves, and dangerous enemies at home!

      This verse here, gives an end to the argument about Ohud by giving a general Law that: ``Allah will not leave the believers as they are until He makes distinct those pure in faith from those that are impure.''

      This is a general law that whoever claims to be a believer will be tested as a part of a universal plan of God, in order to disclose his truthfulness or falsehood.

      In the second part of the verse, it implies that: ``Allah will not inform us of the secrets of the unseen.'' This is because having information about unseen and the future, will not solve any of our problems or difficulties, and sometimes it may render our affairs more critical and complex! Man who is naturally created weak, would be miserable if he could see the unseen and know the unknown - such as his future, his death, and the events after his death. The prophets are excluded from this unawarness, and through choosing them, from time to time some necessary secrets are revealed to man by them as may be expedient.

      The verse ends in that; the present life is a field of examination and tests, in order to separate the believers from the unbelievers, and the pure from impure, and bad from good ones!

      If you want to fail not in your exams, you have to adhere to Allah and to His Messengers, and sincerely believe in them; that if you do believe in Allah and His apostles you shall have a great reward.