Yerushalmi Bava Batra 4:3 ירושלמי בבא בתרא ד׳:ג׳

MISHNAH: He who sold a house sold the door²¹The door, while movable, is permanently connected to the building. But the key is removable. Anything built-in is sold, anything movable is not sold. but not the key. He sold a built-in mortar but not a movable one. He sold the pine cone but not the enclosure²²These two terms, referring to the grain mill, are explained in Chapter 2, Notes 17,18.. He sold the oven and the cooking stove²³This is the reading of the Yerushalmi, Maimonides’s autograph, and the Mishnah mss. in the Maimonides tradition. In the Babli and the Mishnah mss. of the Babylonian tradition: “Neither the oven nor the cooking stove.” As explained in Halakhah 2:1, a (movable) oven or stove may be used inside a house only if it sits on a masonry basis. Therefore it is clear that the bases for oven or stove are sold; oven and stove themselves are not sold. Both versions lead to the same result.. But if he said to him, “it and all it contains,” all is sold.

HALAKHAH: “He who sold a house,” etc. So is the Mishnah: He sold the hewn mortar but not the affixed one²⁴The same text is in the Babli, 65b. There, the commentary ascribed to R. Gershom gives the correct interpretation. A mortar hewn into rock is clearly part of the house and cannot be removed. Any mortar brought from the outside, even if it was permanently affixed to the house, can be removed and therefore is not part of the building which was sold..