Abd al Rahman ibn Nasr ibn Abdallah al Sayzari, Syrian author. Abd-al-Raḥman is mentioned as physician in Aleppo around 1169AD. Nihayat al-rutba (al-zarifa) fi talab al-hisba (al-sarifa), is a major compendium. The first part contains ten chapters on: the secrets of men, and discusses various drugs, nutriments, powders, ointments, and electuaries said to stimulate or reduce sexual appetite, strengthen the potentia erectiva, or induce or prevent conception. The second part contains ten chapters on: the secrets of women and deals with female beauty, intimate cosmetics, perfumes, and the casting of erotic spells by use of talismans and the occult properties of objects. Basically a compilation of prescriptions. We only use a paragraph on selling slaves.

Taken from: Ronald Paul Buckley: The book of the Islamic market inspector
Full name: Shayzari, ‘Ali al-Rahman ibn Nasr ibn ‘Abd Allah

Traders in slaves and animals
The slave-trader  must be trustworthy, reliable and honest, well known for his integrity and respectability. This is because he is responsible for the people’s male and female slaves and is occasionally alone with them in his house.
The trader must not sell a female or a male slave to someone unless he knows the seller or can find someone who knows him. He must write the seller’s name and description in his register in case the person sold is a freeman or has been stolen.
Anyone who wants to buy a female slave may look at her face and palms, but if he asks to examine her in his house and be alone with her the trader must not allow it unless there are other women present. These may see her whole body. Whoever wants to buy a male slave may look at what is above the navel and below the knees. All this may be done before the contract of sale. After the contract, the man may look at all the body of a female slave.
It is not permitted to separate a female slave and her child before seven years have elapsed. Nor it is permitted to sell to a dhimmi (2)(non-Muslim) a female or male who might be a Muslim. The trader must be absolutely certain that the slave is not a Muslim. Whenever the trader knows that a person for sale has a defect, he must reveal this to the buyer, as we mentioned at the beginning of the book.
The slave-trader must be well acquainted with defects and experienced in incipient illnesses and diseases. If he wants to sell a male slave, he must first examine all his body except for his genitals. He does this so that if the slave has a defect or an illness he can inform the buyer of it. The first thing he should look at is his face, for if it is somewhat yellow or ashen this indicates hemorrhoids or a disease or illness in the liver or the spleen.

Al-Shayzari : Al Idahfi Asrar Al-Nikahde Al Sayzari (d1193)
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Taken from: MIGUEL ÁNGEL LUCENA ROMERO: LA SEXUALIDAD ÁRABE E ISLÁMICA MEDIEVAL A TRAVÉS DE LA TRADUCCIÓN DEL KITĀBAL-ĪḌĀḤFĪ ASRĀR AL-NIKĀḤDE AL-ŠAYZARĪ

Know that Byzantine women are the cleanest in the womb, the Andalusians are the most beautiful in appearance, the most penetrating in smell, the most praised for their offspring and the best wombs. Turks and Mongols are the dirtiest in the womb, the fastest in childbirth and the ones with the worst morale. Those from Sind (3), from India and the slaves (saqaliba) (1) are the most unpleasant, the ugliest, the most spiteful, the most mindless, the ones with the worst domestic government, the most smelly and with a dirty uterus. East African women (Zany) are the most foolish and thick. However, if it were the case that you slept with one of them that was beautiful, it will be unmatched with any type described, since their bodies are softer than those of any other.

(1) saqaliba: the Slaves from Eastern Europe.

(2) Dhimmi: The word literally means "protected person”. Historically, dhimmi status was originally applied to Jews, Christians, and Sabians, who are considered to be "People of the Book" in Islamic theology.

(3) Sindh; now part of Pakistan.