thus it is not permissible to sell it, just like human excrement.

Section: It is not permissible to sell a free person, nor that which is not owned, such as permissible resources before they are acquired and possessed. We know of no disagreement regarding this. For the Prophet (may Allah bless him and grant him peace) said: "Allah the Almighty said: 'There are three whom I will oppose on the Day of Resurrection: a man who gave in My name and then betrayed, a man who sold a free person and consumed his price, and a man who hired a laborer, received full service from him, and did not pay his wage.'" Narrated by al-Bukhari (13).

772 - Issue; he said: (And the sale of a cheetah, and a trained falcon, is permissible; likewise the sale of a cat, and everything in which there is benefit.)

The summary of this is that every owned item whose benefit is permitted may be sold, except for what the Sharia has excluded, such as the dog, the Umm al-Walad (a slave woman who has borne her master a child), and the Waqf (endowment). Regarding the Mudabbar (a slave granted freedom after the master's death), the Mukatab (a slave in a manumission contract), and impure oil, there is disagreement, which we will mention in its proper place, if Allah Almighty wills. This is because ownership is a cause (1) for unrestricted disposal, and it is permissible for one to obtain the benefit of what is permitted; therefore, it is permissible for him to take compensation for it, and it is permissible for others to spend their wealth on it to acquire it and fulfill their needs through it, just like all other things whose sale is permitted. This is the same whether it is pure, such as clothing, real estate, livestock, horses, and game animals (2), or whether its impurity is disputed, such as mules, donkeys, and beasts of prey and birds of prey that are suitable for hunting, such as the cheetah, the falcon, the hawk, the peregrine falcon, the eagle, and birds valued for their song, such as the lark, the nightingale, the parrot, and the like. All of these may be sold. This is the view of al-Shafi'i. Abu Bakr Abd al-Aziz and Ibn Abi Musa said: