Is it such a fast
tsowm  (tsome)
a fast: --fast(-ing).
that I have chosen
bachar  (baw-khar')
to try, i.e. (by implication) select -- acceptable, appoint, choose (choice), excellent, join, be rather, require.
a day
yowm  (yome)
a day (as the warm hours),
for a man
'adam  (aw-dawm')
ruddy i.e. a human being (an individual or the species, mankind, etc.) -- another, + hypocrite, + common sort, low, man (mean, of low degree), person.
to afflict
`anah  (aw-naw')
to depress literally or figuratively, transitive or intransitive (in various applications, as follows)
his soul
nephesh  (neh'-fesh)
a breathing creature, i.e. animal of (abstractly) vitality; used very widely in a literal, accommodated or figurative sense (bodily or mental)
is it to bow down
kaphaph  (kaw-faf')
to curve -- bow down (self).
his head
ro'sh  (roshe)
the head (as most easily shaken), whether literal or figurative (in many applications, of place, time, rank, itc.)
as a bulrush
'agmown  (ag-mone')
a marshy pool (others from a different root, a kettle); by implication a rush (as growing there); collectively a rope of rushes -- bulrush, caldron, hook, rush.
and to spread
yatsa`  (yaw-tsah')
to strew as a surface -- make (one's) bed, lie, spread.
saq  (sak)
a mesh (as allowing a liquid to run through), i.e. coarse loose cloth or sacking (used in mourning and for bagging); hence, a bag (for grain, etc.) -- sack(-cloth, -clothes).
and ashes
'epher  (ay'-fer)
ashes -- ashes.
under him wilt thou call
qara'  (kaw-raw')
to call out to (i.e. properly, address by name, but used in a wide variety of applications)
zeh  (zeh)
the masculine demonstrative pronoun, this or that
a fast
tsowm  (tsome)
a fast: --fast(-ing).
and an acceptable
ratsown  (raw-tsone')
delight (especially as shown) -- (be) acceptable(-ance, -ed), delight, desire, favour, (good) pleasure, (own, self, voluntary) will, as...(what) would.
yowm  (yome)
a day (as the warm hours),
to the LORD
Yhovah  (yeh-ho-vaw')
(the) self-Existent or Eternal; Jehovah, Jewish national name of God -- Jehovah, the Lord.