Tirmidhi

Benefits and Issues:
Explanation:
Whatever the slave earned belongs to the buyer.
If, during this period, any defect in him is discovered and he is returned, then only the slave will be returned.
His earnings will not be returned.
Because, hypothetically, if during these days the slave had died,
then this loss would have been borne by the buyer alone.

Benefits and Issues:
Explanation:
In this case, most likely Mukhlad had the work done without the agreement of his partner.
Therefore, the slave became his responsibility (guarantee).
If there had been agreement with the partner, then he too would have had a share in its income.
(From the translation of Allamah Waheed uz-Zaman)

Benefits and Issues:
➊
If something that generates income is purchased and then returned, for the days that item remained with the buyer and he benefited from it, at the time of return, no compensation will be paid for that benefit.
The only exception to this rule is a milk-giving animal, for which, when it is returned, one sa‘ (a measure) of dates will be given along with it.

➋
If the animal dies while with the buyer, or if any other item is damaged or destroyed, then the buyer will bear this loss. Therefore, if the buyer gains any income from it, he will keep it himself; when returning the purchased item, he will not return the income derived from it to the seller.

➌
Our esteemed researcher has declared the aforementioned narration weak in terms of its chain of transmission. However, this same narration is also found in Sunan Abi Dawud (3510), where our researcher has written regarding it that this narration is weak in its chain, but the previous narration (3509) suffices for it. Therefore, according to our esteemed researcher, despite this narration being weak in its chain, it is correct in meaning and practicable. Moreover, other researchers have graded this narration as hasan (good).
—See: (Sahih Sunan Ibn Majah by al-Albani, no. 1836, and al-Mawsu‘ah al-Hadithiyyah Musnad al-Imam Ahmad: 40/272, 273)

For example: If a person bought an animal, and after a few days a defect or deception was discovered in it, then the sale is annulled. However, the milk and similar benefits obtained from the animal during the days it remained with the buyer will belong to him, because if the animal had suffered any loss during those days, the responsibility would have fallen upon the buyer. Similarly, during those days, the responsibility for its feed and other expenses was also upon him.