Charles Ellicott Commentary Judges 15:9

"Then the Philistines went up, and encamped in Judah, and spread themselves in Lehi." — Judges 15:9 (ASV)

Then the Philistines went up. —They “went up” in hostile array against the hill-country of Judea to take vengeance for the dreadful injury which Samson had inflicted on them.

Spread themselves in Lehi. —This practice of using a place's name before the incident from which it is said to have received that name is also found in the case of Hormah (Numbers 14:45; Numbers 21:3). It was called in full Ramath-Lehi. (See commentary on Judges 15:17.) The character of the narrative raises the question of whether the name might have existed previously, and whether the play on words was adapted by Samson to the incident.

For the name of the place is Lechi (לֶ֫חִי), and “a jawbone” is Lehi (להי). Shen, meaning “tooth,” is the name of an isolated sharp rock (1 Samuel 14:4), and therefore “jaw” would not be an unnatural name for a range of such rocks. Josephus, however, says that before Samson’s exploit the place “had no name.” It may be alluded to again in 2 Samuel 23:11, where the words rendered “into a troop” may mean “to Lehi,” as understood by Josephus (Antiquities 7.12.4) and some manuscripts of the Septuagint.