They shall not labour
yaga`  (yaw-gah')
to gasp; hence, to be exhausted, to tire, to toil -- faint, (make to) labour, (be) weary.
in vain
riyq  (reek)
emptiness; figuratively, a worthless thing; adverbially, in vain -- empty, to no purpose, (in) vain (thing), vanity.
nor bring forth
yalad  (yaw-lad')
to bear young; causatively, to beget; medically, to act as midwife; specifically, to show lineage
for trouble
behalah  (beh-haw-law')
panic, destruction -- terror, trouble.
for they are the seed
zera`  (zeh'-rah)
seed; figuratively, fruit, plant, sowing-time, posterity -- carnally, child, fruitful, seed(-time), sowing-time.
of the blessed
barak  (baw-rak')
to kneel; by implication to bless God (as an act of adoration), and (vice-versa) man (as a benefit); also (by euphemism) to curse (God or the king, as treason)
of the LORD
Yhovah  (yeh-ho-vaw')
(the) self-Existent or Eternal; Jehovah, Jewish national name of God -- Jehovah, the Lord.
and their offspring
tse'etsa'  (tseh-ets-aw')
issue, i.e. produce, children -- that which cometh forth (out), offspring.
with them