وَحَمَلْنَاهُمْ عَلَى حَزْمِ ثَهْلَانَ شِلَالًا وَدَمِيَ الْأَنْسَاءُ
Meaning: We drove them towards the heights of Thahlān, scattering in flight with the sinews of their thighs wounded.
Ḥazm denotes a rise or tract of firm elevated ground, and Thahlān is the name of a mountain. Shilālan conveys rapid and scattered movement.
The commentary explains al-ansāʾ as the plural of a term for a known sinew or vessel in the thigh. Damiya introduces blood or injury. The preceding general picture of defeat is thus placed in a specific landscape and given a physical consequence.