How can it be quiet
shaqat (shaw-kat')
to repose (usually figurative) -- appease, idleness, (at, be at, be in, give) quiet(-ness), (be at, be in, give, have, take) rest, settle, be still.
seeing the LORD
Yhovah (yeh-ho-vaw')
(the) self-Existent or Eternal; Jehovah, Jewish national name of God -- Jehovah, the Lord.
hath given it a charge
tsavah (tsaw-vaw')
(intensively) to constitute, enjoin -- appoint, (for-)bid, (give a) charge, (give a, give in, send with) command(-er, -ment), send a messenger, put, (set) in order.
against Ashkelon
'Ashqlown (ash-kel-one')
Ashkelon, a place in Palestine -- Ashkelon, Askalon.
and against the sea
yam (yawm)
from an unused root meaning to roar -- sea (-faring man, (-shore), south, west (-ern, side, -ward).
shore
chowph (khofe)
a cove (as a sheltered bay) -- coast (of the sea), haven, shore, (sea-)side.
there hath he appointed
ya`ad (yaw-ad')
to fix upon (by agreement or appointment); by implication, to meet (at a stated time), to summon (to trial), to direct (in a certain quarter or position), to engage (for marriage)
it