Bukhari

Hadith Commentary:
From the Qur’anic verse and both ahadith, Imam Bukhari rahimahullah has established that the earnings of a prostitute and the earnings of a slave-girl (through prostitution) are forbidden (haram).
In the era of ignorance (Jahiliyyah), people used to obtain unlawful earnings from their slave-girls and would forcibly make them practice this profession.
Islam has strictly prohibited this and has declared such earnings to be unlawful (haram) sustenance.
Similarly, the profession of soothsaying (kahānah) has also been declared forbidden, and the price of a dog has likewise been prohibited.

Hadith Commentary:
By the earnings of slave girls is meant obtaining payment through committing fornication.
This is forbidden, as we have already explained earlier; however, the skillful work of their hands and the income derived from that is permissible.

(2)
In any case, from the Qur’anic verse and both of the aforementioned hadiths, Imam Bukhari rahimahullah has established that the earnings of a prostitute and the earnings of a slave girl through prostitution are forbidden.
In the era of ignorance (Jahiliyyah), some people would make their slave girls engage in prostitution and then consume the unlawful earnings; Islam strictly prohibited prostitution and declared such income to be unlawful (haram) sustenance.

Hadith Commentary:
Hafiz said: If someone deliberately marries a woman who is a mahram to him, such as his mother, sister, daughter, etc., knowing that it is forbidden, then the prescribed punishment (hadd) will be carried out upon him.
This is the same legal verdict (fatwa) of the three Imams and the Ahl al-Hadith.
This crime is so grave that eliminating the perpetrator is true justice.

Hadith Commentary:
(1)
Imam Bukhari rahimahullah has clarified in this chapter heading and the presented ahadith the rulings regarding the dower (mahr) in an invalid marriage (nikah fasid) and the wage for fornication (zina).
The wage that is given in exchange for fornication is called mahr al-baghi.
This is forbidden, and there is no difference of opinion regarding its prohibition, because fornication is forbidden, and therefore its compensation is also unlawful and forbidden.
Similarly, the wage of a female singer and a professional mourner is also forbidden.
However, in an invalid marriage (nikah fasid), the woman is given her stipulated dower (mahr), and immediately after that, separation is effected between them.

(2)
An invalid marriage (nikah fasid) is one that is contracted without witnesses or without the permission of a guardian (wali).
Similarly, marrying during the waiting period (‘iddah) or marrying someone for a fixed period (temporary marriage) is also considered an invalid marriage (nikah fasid). In such a marriage, the woman receives her stipulated dower (mahr); apart from this, she is not entitled to anything else.

(3)
The earning from slave-girls (kasb ama’) refers to making slave-girls commit fornication and taking compensation for it.
This compensation is also forbidden and is included in the earnings of a fornicating woman.
And Allah knows best.

Benefits and Issues:
Benefit:
That is, when a slave-girl earns wealth through fornication or singing and music, it is entirely unlawful (haram).