isaiah 65:20 There shall be no more thence an infant of days, nor an old man that hath not filled his days: for the child shall die an hundred years old; but the sinner being an hundred years old shall be accursed. - Free Bible Online

      20. The longevity of men in the first age of the world shall be enjoyed again.
      thence--from that time forward.
      infant of days--that is, an infant who shall only complete a few days; short-lived.
      filled . . . days--None shall die without attaining a full old age.
      child . . . die . . . hundred years--that is, "he that dieth an hundred years old shall die a mere child" [LOWTH].
      sinner . . . hundred . . . be accursed--"The sinner that dieth at an hundred years shall be deemed accursed," that is, his death at so early an age, which in those days the hundredth year will be regarded, just as if it were mere childhood, shall be deemed the effect of God's special visitation in wrath [ROSENMULLER]. This passage proves that the better age to come on earth, though much superior to the present will not be a perfect state; sin and death shall have place in it (compare Re 20:7, 8), but much less frequently than now.

JFB.