Bava Batra 78 - Selling a Donkey
If one sells a donkey to his fellow, he has not sold its gear. Nachum the Mede, however, says, he has sold his gear, too.
All agree that the saddle, the blanket, the girth that goes under donkey's belly, and the breast strap are sold. These are necessary for the use of the donkey. They argue about the sack and saddlebag, which are specifically cargo gear. The first teacher holds that ordinarily a donkey is used for riding, and the cargo gear is therefore not included in the sale. Nachum holds that ordinarily a donkey is used for transporting cargo, and therefore its cargo gear is included in the sale.
Is the argument about the gear that is on the donkey, or the gear that is not? This question remains unresolved, and the one who wants to extract money from his fellow needs to prove his right.