Book Name: The Unique Contract
The author: Abu Omar, Shihab al-Din Ahmad bin Muhammad bin Abd Rabbo bin Habib bin Hudayr bin Salem, known as Ibn Abd Rabbo Al-Andalusi (deceased: 328 AH)

The book of Ibn Abd Rabbo, who immortalized his memory in the world, was written at a time when Cordoba was at the height of its prosperity. It is customary for it to be said when it is mentioned that when the letter fell to the companion Ibn Abbad, he said: This is our merchandise that has been returned to us. However, his approach in dividing and coordinating the book endeared him to lovers of literature, so they circulated it, and it became popular in the East, as Muhammad Kurd Ali says throughout the ages, although he had marketed it from the goods and markets of the East.