Is it Islamically permissible to purchase a building (a house or an apartment building) without the land, and which one follows the other when contracting for either of them absolutely?

If a building is sold, and the contract does not specify whether the land is included or excluded, and there is no customary practice regarding this, then the land is included in the sale according to the four madhhabs. However, if a piece of land with a building on it is sold, and the contract does not specify whether the building is included or excluded, and there is no customary practice regarding this, then the majority of jurists hold that the building is included in the sale due to its attachment to the land and its rights.