He says, keep, i. e. not by faith, but by purity of life. And at the same time too He means it as a tacit intimation that they can do nothing to Him. For if whoever keepeth His word, shall never die, much less is it possible that He Himself should die.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Hom. lv. 1