(Among the believers are men who have been true to their covenant with Allah [i.e. they have gone out for Jihad (holy fighting), and showed not their backs to the disbelievers], of them some have fulfilled their obligations (i.e. have been martyred), and some of them are still waiting, but they have never changed [i.e.they never proved treacherous to their covenant which they concluded with Allah] in the least.)
(Al-ahzab-23)
