There was less tampering and big talk then
from Unferth the boaster, less of his blather
as the hall-thanes eyed the awful proof
of the hero’s prowess, the splayed hand
up under the eaves. Every nail,
claw-scale and spur, every spike
and welt on the hand of that heathen brute
was like barbed steel. Everybody said
there was no honed iron hard enough
to pierce him through, no time-proofed blade
that could cut his brutal, blood-caked claw.

Beowulf, Seamus Heaney (trans.)

Lines 979-989: It is not sufficient for Beowulf to recount stories of his physical prowess, but he needs to show evidence of his great deeds, like Grendel’s severed arm hanging up in Heorot Hall.