(Mishnah): If Shimon brought his ox into Reuven's yard without permission, and Reuven's ox gored it, or Reuven's dog bit it, he is exempt;

If the ox gored Reuven's ox, he is liable. If it fell into a pit and dirtied the water, he is liable;

If Reuven's father or son was inside the pit, Shimon pays Kofer;

If Shimon had permission to bring his ox in, [Reuven] is liable.

Rebbi says, in all cases [Reuven] is liable only if he accepted to guard [Shimon's property].

(Gemara): If Shimon brought his ox into Reuven's yard without permission, and an ox came from elsewhere and gored, pushed, bit, crouched or kicked it, [the owner] pays full damage. R. Meir says so;

Chachamim say, for Shen and Regel he is liable [full damage]. For goring, pushing [with the horns], biting, crouching, kicking or pushing [with the body], a Tam pays half-damage and a Mu'ad pays full damage from the Aliyah.

(Rav Yehudah citing Shmuel): The Halachah follows Rebbi [in our Mishnah].

(R. Yirmeyah): All agree that in a house, [when he gives permission Stam,] he says (means) 'enter, and I will guard it.' All agree that in a field, he says 'enter it, and [you must] guard it';

What do they argue about? They argue about a Chatzer. Rebbi says, a Chatzer is like a field. Chachamim say, a Chatzer is like a house.

Question (Mishnah): If one made stacks in Levi's field without permission... [if he had permission and Levi's animal ate them, he is liable]. Stacks in a field are like Kelim in a house! (This shows that a field is like a house!)

Answer (R. Yosi bei R. Bun): That discusses [an enclosed field with a lock. It is like a house, but a Stam field is not.]