Cast me not off
shalak (shaw-lak)
to throw out, down or away -- adventure, cast (away, down, forth, off, out), hurl, pluck, throw.
in the time
`eth (ayth)
time, especially (adverb with preposition) now, when, etc.
of old age
ziqnah (zik-naw')
old age -- old (age).
forsake
`azab (aw-zab')
to loosen, i.e. relinquish, permit, etc. -- commit self, fail, forsake, fortify, help, leave (destitute, off), refuse, surely.
me not when my strength
koach (ko'-akh)
from an unused root meaning to be firm; vigor, literally (force, in a good or a bad sense) or figuratively (capacity, means, produce); also (from its hardiness) a large lizard
faileth
kalah (kaw-law')
to end, whether intransitive (to cease, be finished, perish) or transitived (to complete, prepare, consume)