Baldness is come upon Gaza. — The baldness is the outward sign of extremest mourning (Jeremiah 48:37; Isaiah 15:2-3), perhaps, also, of extremest desolation (Isaiah 7:20).
Ashkelon is cut off... — Better, perhaps, Ashkelon is speechless. The LXX. apparently followed a different text, and gives “the remnant of the Anakim” instead of “the remnant of their valley.” Hitzig adopts this rendering, and connects it with the known fact that a remnant of the old gigantic non-Semitic race had taken refuge among the Philistines (1 Samuel 17:4; 2 Samuel 21:22; 1 Chronicles 20:5-8) after they had been driven from Hebron (Joshua 14:12-15; Joshua 15:13-14). Others, without adopting the LXX. reading, interpret the word rendered “their valley” as meaning, as in Isaiah 33:19, those that speak an unintelligible language, barbarians (Amakim), and suppose this form to have passed in the LXX. into the more familiar form of Anakim. The English version, however, is accepted by many critics, and may refer to Ashkelon and Gaza as the “remnant,” the last resource of the valley (Emek) or low-country of the Philistines, more commonly known as the Shephelah.
How long wilt thou cut thyself? — The words point to a ritual of supplication, like that of the priests of Baal in 1 Kings 18:28, as prevailing among the Philistines.