This is a passage from Sir Gawain and the Green Knight. In an impressive display of bravery and honor, Sir Gawain steps up to take King Arthur's place in the Green Knight's game. Gawain is surprised that the other knights in Arthur's court willingly let King Arthur accept the challenge:

I find it not fit, as in faith it is known,
When such a boon is begged before all these knights,
Though you be tempted thereto, to take it on yourself
While so bold men about upon benches sit,
That no host under heaven is hardier of will,
Nor better brothers-in-arms where battle is joined;
I am the weakest, well I know, and of wit feeblest;
And the loss of my life would be least of any;
That I have you for uncle is my only praise;
My body, but for your blood, is barren of worth;
And for that this folly befits not a king. (Green Knight 348-358)