«وَلَا جَعَلْتُ هَامَتَهُ لِسَيْفِي غِمْدًا»
Nor did I make his head a sheath for my sword.
Hāmah is the head and ghimd a scabbard. A striking metaphor treats the victim’s head as something that could receive a blade. This is imagery within the elder’s demanded oath, not evidence that such an attack occurred.