“It’s just as if a man were wounded with an arrow thickly smeared with poison. His friends & companions, kinsmen & relatives would provide him with a surgeon, and the man would say, ‘I won’t have this arrow removed until I know whether the man who wounded me was a noble warrior, a priest, a merchant, or a worker.’ He would say, ‘I won’t have this arrow removed until I know the given name & clan name of the man who wounded me… until I know whether he was tall, medium, or short… until I know whether he was dark, ruddy-brown, or golden-colored… until I know his home village, town, or city… until I know whether the bow with which I was wounded was a long bow or a crossbow… until I know whether the bowstring with which I was wounded was fiber, bamboo threads, sinew, hemp, or bark… until I know whether the shaft with which I was wounded was wild or cultivated… until I know whether the feathers of the shaft with which I was wounded were those of a vulture, a stork, a hawk, a peacock, or another bird… until I know whether the shaft with which I was wounded was bound with the sinew of an ox, a water buffalo, a langur, or a monkey.’ He would say, ‘I won’t have this arrow removed until I know whether the shaft with which I was wounded was that of a common arrow, a curved arrow, a barbed, a calf-toothed, or an oleander arrow.’ The man would die and those things would still remain unknown to him.”
From Wikipedia: The sutta’s origins are at Jetavana where the monk Malunkyaputta is troubled by Gautama Buddha’s silence on the fourteen unanswerable questions, which include queries about the nature of the cosmos and life after the death of a Buddha. Malunkyaputta then meets with Gautama Buddha and asks him for the answers to these questions, he says that if he fails to respond, Malunkya will renounce his teachings. Gautama responds by first stating that he never promised to reveal ultimate metaphysical truths such as those and then uses the story of a man who has been shot with a poisoned arrow to illustrate that those questions are irrelevant to his teachings.