Carl Friedrich Keil and Franz Delitzsch Old Testament Commentary

"Then he smote them hip and thigh (lit. 'thigh upon hip;' על as in Gen 32:12), a great slaughter." שׁוק, thigh, strengthened by על־ירך, is a second accusative governed by the verb, and added to define the word אותם more minutely, in the sense of "on hip and thigh;" whilst the expression which follows, גדולה מכּה, is added as an adverbial accusative to strengthen the verb ויּך. Smiting hip and thigh is a proverbial expression for a cruel, unsparing slaughter, like the German "cutting arm and leg in two," or the Arabic "war in thigh fashion" (see Bertheau in loc.). After smiting the Philistines, Samson went down and dwelt in the cleft of the rock Etam. There is a town of Etam mentioned in Ch2 11:6, between Bethlehem and Tekoah, which was fortified by Rehoboam, and stood in all probability to the south of Jerusalem, upon the mountains of Judah. But this Etam, which Robinson (Pal. ii. 168) supposes to be the village of Urtas, a place still inhabited, though lying in ruins, is not to be thought of here, as the Philistines did not go up to the mountains of Judah (Jdg 15:9), as Bertheau imagines, but simply came forward and encamped in Judah. The Etam of this verse is mentioned in Ch1 4:32, along with Ain Rimmon and other Simeonitish towns, and is to be sought for on the border of the Negeb and of the mountains of Judah, in the neighbourhood of Khuweilifeh (see V. de Velde, Mem. p. 311). The expression "he went down" suits this place very well, but not the Etam on the mountains of Judah, to which he would have had to go up, and not down, from Timnath.