(Exodus 22:12) discusses an animal that is "torn by a wild beast" while in a guardian's care: "If it were torn, let him bring ed." But what does "ed" mean? Two rabbis disagreed.
Rabbi Yoshiyah said "ed" means the hide — the physical remains of the torn animal. The guardian must bring proof that the animal was indeed killed by a predator. Even without direct proof, the idea is supported by (Amos 3:12): "Just as a shepherd can rescue from the mouth of a lion just two legs or the cartilage of an ear." The shepherd brings whatever scraps survive the attack as evidence that the predator, not negligence, caused the loss.
Rabbi Yochanan ben Yoshiyah offered a completely different reading. He said "ed" means "edim" — witnesses. The guardian must bring human witnesses who can testify that the animal was torn by a wild beast. Rather than presenting physical evidence, he presents testimonial evidence.
Both readings produce the same practical result — the guardian is exempted from paying for the loss — but through different mechanisms. One requires physical proof (the carcass or fragments). The other requires witness testimony. The Mekhilta preserves both interpretations, recognizing that either form of evidence could serve justice. The torn animal is the guardian's strongest defense, and the law gives him two ways to present it: show what remains, or produce someone who saw what happened.