Is it permissible to sell a property or building without selling the land it is built upon, while the seller retains ownership of the land?

It is permissible to sell a building without the land upon which it is built, provided this is explicitly stated. If a house is sold and it is not specified that the land is not included in the sale, then the land is included in the sale. However, if it is stipulated that the building is sold separately without the land, then the land is not included in the sale, and the condition or custom takes precedence if it contradicts the original principle.