John Gill Commentary Jeremiah 47:7

"How canst thou be quiet, seeing Jehovah hath given thee a charge? Against Ashkelon, and against the sea-shore, there hath he appointed it." — Jeremiah 47:7 (ASV)

How can it be quiet
There is no reason to believe it will, nor can it be expected that it should; to stop it is impossible, and to request that it might be stopped is in vain: seeing the Lord has given it a charge against Ashkelon, and against
the seashore ?
for it had a commission from the Lord to destroy the inhabitants of Ashkelon, and other places, which lay still more towards the sea, as Joppa and Jamne; and indeed all Palestine lay on the coast of the Mediterranean sea: there has he appointed it ;
by an irreversible decree of his, in righteousness to punish the inhabitants of these places for their sins.