That is, He who shall not let go the commands of the faith, nor fall away in persecution, shall be saved; he shall receive the reward of the heavenly kingdom for his earthly persecutions. And note that ‘the end’ does not always mean destruction, but sometimes perfection, as in that, “Christ is the end of the Law.” [Rom 10:4] So the sense here may be, “Whosoever shall endure to the end,” that is, in Christ.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).