Bava Basra, Chapter 4, Mishnah 3. This is the third and final mishnah in the series of mishnayos dealing with a person who sells his house without defining exactly what is included in that sale.
Selling a house - what is included in the sale:
"Hamocher es habayis - machar es hadelet" - The essential parts of the house that are attached to it are certainly included in the sale. The seller is not permitted to take the doors with him.
"Aval lo es hamafte'ach" - The key is not attached to the door, nor is it part of it or the house, and it can even be used elsewhere. Therefore, the seller is permitted to take the key with him, and the buyer will have to arrange for a new key.
"Machar es hamachteshes hakvu'ah" - A machteshes is the bowl in which one pounds using a pestle. Some commentaries explain that this refers to a mortar attached to the ground (with mud and cement), and others explain that it is built into the ground near the house. The point is that it is considered part of the house, as every house needs a place to pound its necessities. Because of this, a mortar fixed to the ground is sold together with the house.
"Aval lo es hamitalteles" - A movable mortar is not included in the sale, and the seller is permitted to take it with him and is not obligated to leave it for the buyer.
"Machar es ha'itrovul" - This refers to a house that has a hand mill, two heavy stones that move on top of one another and grind wheat. According to the Bartenura, the itrovul is a wooden base attached to the ground, upon which the millstones are placed. It seems its purpose is to absorb the vibrations, as we saw in the second chapter that a person is not permitted to grind near his neighbor's wall because the vibrations damage his building. Since the base is attached to the ground, it remains with the house and is sold with it.
"Aval lo es hakelas" - The kelas is a removable receptacle that catches the wheat flour coming out of the millstones, and it is not included in the sale.
"Bizman she'amar lo hu vechol mah shebesocho":
If the seller said that he is selling the house "and everything inside it" - "harei kulan mechorin" - they are all sold. But what is "everything"? This refers to all the items listed in this mishnah: not only the door, but also the key, the mortar and the movable mortar along with it, as well as the movable parts of the millstones and the kelas that catches the flour. These items are the essential components of a normal house, and therefore they remain in it.
However, this does not include what we saw in the previous two mishnayos: even one who says "everything inside it" did not include in his sale the second floor, the cistern in the cellar, and similar things - these are not considered "inside it".
Furthermore, even though there is a dispute among the Rishonim regarding this, the simple understanding is that furniture is not included in the sale. One who says "everything inside it" intends only the essential parts of the house, even if they are not attached to it. Movable items - such as food and clothing - are certainly not included in the sale, and even the household furniture is not included, as the seller does not intend to include things that a person takes with him to his new home.
In summary: In this mishnah, we learned that in a standard sale of a house, the attached and fixed parts are included - the door, the fixed mortar, and the itrovul - whereas the movable parts - the key, the movable mortar, and the kelas - remain in the hands of the seller. One who says "and everything inside it" includes even the movable items listed in the mishnah, but not the second floor and the cistern from the previous mishnayos, nor the furniture and household objects.