The ruling on selling what is in the wombs and backs, and an explanation of the cancellation of a sale

The Shaykh:
Rather, all of this is obligatory and not valid. Even if there is weakness in the chain of the hadith, the meaning is correct; the meaning is that it is not valid, because this is a purpose contrary to nature, which is not permissible. One only sells something that exists and is sound, such as an existing camel, an existing goat, or an existing cow, even if it is small, or other existing things that can be seen. As for what is in the wombs and backs, it is not sold. The second hadith says: The Prophet (peace and blessings be upon him) said: He sold it, he said: It is its hair, this is regarding the cancellation of the sale. The meaning of the cancellation of the sale is the rescission of the contract, because the buyer may be harmed; he may request the cancellation of the sale because he feels he was deceived, or for other reasons. It is prescribed for his brother to cancel the sale for him if he sees that he needs the cancellation, and perhaps Allah will provide him with something better. If he bought from him a house, a car, a beast, land, or something else, and then he regretted it and said, "My brother, cancel the sale for me, I will give you all my money and give me my price back," it is recommended for him to cancel the sale for him if it is easy to give him his price back. It is recommended to cancel the sale, but the sale is binding due to the prohibition of tawarruq (a commodity sale used to obtain cash). However, if he cancels the sale for him and meets his need, the Muslim is the brother of the Muslim, which obligates this. If he says, "Islam..." If he says, "Allah affirmed it," and Allah the Exalted says: But it is not obligatory for him to cancel the sale unless there is a legal reason, such as deception, or being overcharged, or betrayal. If not, he is not obligated to cancel it, but it is recommended for him to cancel the sale, and if he did not...