Bava Kamma 35A

אף הוא נמי דלא קבעי ליה; וקתני: פטור ⁠– מפני שהוא נדון בנפשו!

so too, in the case where he set the fire, it is presumably a case where he does not need the ashes. And nevertheless, the Mishnah teaches that he is exempt because he is sentenced to death. Apparently, one who lights a fire on Shabbat is liable even if he does not need the ashes, contrary to the opinion of R' Yoḥanan.

לא; שורו דומיא דידיה ⁠– מה הוא דקבעי ליה, אף שורו דקבעי ליה.

The Talmud rejects this proof: No, the comparison is the other way around; the case where his ox set the fire is similar to the case where he set the fire. Just as the case where he is liable for lighting a fire on Shabbat is one where he needs the ashes, so too, the case of his ox setting fire to the haystack is one where it needs the ashes.

שורו היכי משכחת לה? אמר ליה רב אויא: הכא במאי עסקינן ⁠– בשור פקח שעלתה לו נשיכה בגבו, וקא בעי למקלייה ואיגנדר בקוטמא.

The Talmud asks: In the case where his ox set the fire, how can you find these circumstances, where it did so because it needed the ashes? Rav Avya said to him: Here we are dealing with an intelligent ox that was bitten on its back and wants to burn down the haystack and then roll around [iggandar] in the ashes in order to heal the bite.

ומנא ידעינן? דלבתר דקלייה קמגנדר בקוטמא.

The Talmud asks: And from where do we know that this is the reason that it set the fire? The Talmud answers: Because after the ox burned the haystack, it was rolling around in the ashes.

ומי איכא כי האי גוונא? אין; דההוא תורא דהוה בי רב פפא דהוה כיבין ליה חינכיה, עייל ופתקיה לנזייתא, ושתי שיכרא ואיתסי.

The Talmud asks: And is there really a case like this? The Talmud answers: Yes, as a certain ox that was at the house of Rav Pappa had a toothache. It went inside, and broke the lid of a utensil, and drank the liquor inside and was cured. Evidently there are oxen with this level of intelligence.