Albert Barnes Commentary Jeremiah 47:4

"because of the day that cometh to destroy all the Philistines, to cut off from Tyre and Sidon every helper that remaineth: for Jehovah will destroy the Philistines, the remnant of the isle of Caphtor." — Jeremiah 47:4 (ASV)

Because of the day that comes to spoil – “Because” the day has come “to devastate.”

The Philistines are called Tyre’s remaining (that is, last) helper, because all others who could have assisted her have already succumbed to the Chaldean power. The judgment upon Philistia was in connection with that upon Tyre, and it was fulfilled by expeditions sent out by Nebuchadnezzar under his lieutenants to ravage the country and supply his main army with provisions.

The country of Caphtor – The coastland of Caphtor. The Philistines came from the coast of the Egyptian Delta, and are called a remnant because they had been greatly reduced in numbers, partly by the long war of Psammetichus against Ashdod, partly by the capture of Gaza (Jeremiah 47:1), and partly by Assyrian invasions.