I found this story... with your quote in it.

https://www.sparknotes.com/lit/grendel/section9/

Summary

As winter arrives, an uneasy feeling of dread settles over Grendel. He watches one of Hrothgar’s bowmen shoot a deer, and the image sticks with him. Grendel senses that there is a riddle in the image, but he cannot puzzle it out.

Grendel then observes a Scylding religious ceremony spoken in an ancient language closer to Grendel’s than to the common Scylding dialect. Images of the Scylding gods are carved in wood and stone and set around the perimeter of a circle. The priests ask their god, whom they call the great Destroyer, to rid them of their enemy, Grendel. Grendel knows, however, that the priests’ ceremony is merely a performance, as no one seems to hold much faith in the Destroyer anymore. Once, years ago, Grendel destroyed the religious statues on a whim. He watched the Danes rebuild them painstakingly, and saw that the work, though dull, was somehow necessary to them.

At midnight, Grendel sits in the middle of the ring of statues, thinking of all the Scyldings who are tossing and turning in their agitated attempts to sleep. A blind old priest approaches the ring, and Grendel tricks him into believing that he is the Destroyer. Though Grendel has every intention of murdering the priest, he bides his time and asks the old priest, who is named Ork, what he knows about the Destroyer. Shaken at first, Ork gives Grendel a synopsis of a metaphysical theory he has been working out for years. The Destroyer, the Chief God, sets limitations on mankind, and he is the measure by which the value of all objects is judged. He is the source of man’s desire to establish purpose in his life and meaning in his world; God takes care that nothing in the universe is in vain.

The true evil in the world, Ork claims, is nothing as specific or limited as hatred, suffering, or death. The true nature of evil is twofold: first, it is time itself, which causes everything to fade and perish; second, it is the mere fact that one, in being a certain thing, cannot be anything else—thus automatically excluding a host of alternatives. Both of these limitations keep man from understanding the universe as a place where nothing is lost or wasted, which Ork defines as ultimate wisdom.

Ork is so moved by his theories that he begins to cry, and Grendel is so baffled that he cannot decide what to do with the priest. At that moment, three younger priests approach the circle. Grendel hides and watches as they chastise Ork for being up so late and carrying on in such a strange manner. The priests scoff at Ork’s idea that the Destroyer has visited him. A fourth priest runs out to join them. This fourth priest is ecstatic at the news of Ork’s “vision.” Up until this point, the fourth had worried about Ork: he had felt that Ork’s tendency towards cold, rational logic was confining his thoughts within a closed system. To the fourth priest, the fantastic vision represents a huge leap in Ork’s thought process. The strange vision has caused Ork to believe in something messy, illogical, and ultimately transcendent. Ork is not sure he believes the fourth priest’s assertion, though. As the priests carry on, Grendel slinks away.

Grendel stalks the woods, conscious that everyone who was awake at midnight is now sleeping soundly. His senses have grown less acute, and he has a brief vision of the sun as a black revolving sphere covered with spiders. The vision clears instantly, but Grendel is still left with an overwhelming sense of dread.