Bava Basra, Chapter 5, Mishnah 2. We must preface and emphasize once again: These Mishnayos are difficult to understand because they are entirely based on the meaning that words held for people in second-century Eretz Yisrael - a meaning that is completely different from the way we speak today.
The Case: Selling a Donkey:
A donkey has two distinct functions: it serves as a beast of burden for transporting loads, and it is also used for riding. The Mishnah implies that the primary purpose for which people kept a donkey was riding (and as is well known, even the Mashiach will arrive riding on a donkey). Therefore, there are two separate sets of equipment:
Riding equipment - the saddle, stirrups, and the like.
Load-bearing equipment - saddlebags, the blanket that protects the donkey's back from chafing, and similar items.
The question is: When a person buys a donkey without specifying what is included in the sale, which of the equipment sets is included?
The Mishnah takes it as a given that the riding equipment is included, since it is secondary to the donkey and every donkey is used for riding. The uncertainty, therefore, revolves only around the load-bearing equipment.
Three Opinions Regarding Load-Bearing Equipment:
"Ha'mocher es hachamor lo machar keilav" - the opinion of the Tanna Kamma: The load-bearing equipment is not included in the sale. It is not secondary to the donkey but rather a separate entity, and therefore the buyer receives only the riding equipment.
"Nachum HaMadi omer: mocher keilav" - both sets of equipment are included in the sale, including the load-bearing equipment.
"Rabbi Yehudah omer: pa'am mocher ufa'am eino mocher" - the matter depends on the circumstances: sometimes the load-bearing equipment is included and sometimes it is not.
Explanation of Rabbi Yehudah's Opinion:
The Mishnah asks, "Keitzad?", and presents two cases where the distinction between them relies on linguistic nuances that were common in their speech. These distinctions are subtle, and even after the best explanation, the student may remain somewhat puzzled:
"Hayah chamor lefanav vekeilav alav, ve'amar lo: mechor li chamor zeh - harei keilav mechorin" - the donkey is standing before them laden with the load-bearing equipment, and Reuven says to Shimon, the donkey's owner, "Sell me this donkey." Since he specifically pointed to the donkey in its current state, rather than saying, "Sell me your donkey," he is hinting that he wants it exactly as it stands loaded with its equipment - and therefore, the load-bearing equipment is included in the sale.
"Chamor zeh?" - phrased as a question: Reuven asks, "Is this donkey yours?", Shimon answers, "Yes," and Reuven says, "I will buy it from you for a hundred." Here, he did not point to the donkey in its specific state to hint that he also wants the equipment on it, and therefore the equipment is not sold - even though the donkey is wearing the load-bearing equipment at that moment. The load-bearing equipment is not included, while the riding equipment is included as usual.
In summary: The Tanna'im disagreed regarding the law of the load-bearing equipment accompanying a donkey: according to the Tanna Kamma, it is not sold with the donkey; according to Nachum HaMadi, it is sold with it; and according to Rabbi Yehudah, it depends on the buyer's phrasing and the context. The halachah follows the Tanna Kamma, that load-bearing equipment is never included in the sale unless explicitly mentioned.
In practice, nowadays everything depends on the accepted meaning of the statement "I will buy your donkey", and we are unable to determine what that is.