‘Abbasa (765-803) was a daughter of the ‘Abbasid caliph al-Mahdi and the sister of the caliphs Harun al-Rashid and al-Hadi. Her name is connected with the fall of the Barmakids in 803 C.C., because of her alleged love affair.
The Barmakids were a Persian family that had become very powerful during the caliphate of al-Mahdi. Yahya, the vizier of Harun al-Rashid, had aided Harun al-Rashid in obtaining the caliphate. Yahya and his sons were in high favor until 803 when the caliph threw them in prison and confiscated their land. Many reasons are given for this punitive action. Yahya's entering Harun's presence without Harun's permission; Yahya's opposition to Muhammad ibn al-Layth who later gained Harun's favor; and the Barmakid's ostentatious display of their wealth are said to be the cause of Harun's action. However, the reason which has intrigued writers and storytellers for ages is the alleged romantic relationship between Ja'far, the son of Yahya, and Harun's sister, 'Abbasa.
As the story goes, Ja'far, was the constant companion of Harun. Harun was also very fond of his sister, 'Abbasa, and loved to have both her and Jafar around at times of recreation. However, Muslim etiquette forbade their common presence. To circumvent the rules of etiquette, Harun had a marriage ceremony performed between 'Abbasa and Ja'far, but only with the understanding that the ceremony was purely nominal and that 'Abbasa and Ja'far were not to become intimately involved. Unfortunately, the heart of 'Abbasa ignored the ban. She fell in love with Ja'far and became infatuated with him. One night she entered Ja'far's bedroom in the darkness, masquerading as one of his slave girls. She seduced Ja'far and had sex with him.
From this union, a child was conceived. 'Abbasa secretly gave birth to the child and the child was sent by 'Abbasa to Mecca. However, a maid, after quarreling with her mistress, disclosed the scandal. Harun, while on a pilgrimage in Mecca, heard the story and became enraged. Upon his return to Baghdad, Harun had Ja'far executed, his body cut in two, and impaled on either side of the bridge. Harun also had Ja'far's father (Yahya) and brother (al-Fadl) cast into prison. Ja'far's body stayed impaled for three years until when Harun happened to pass through Baghdad from the East, saw the body, and gave the command for the remains to be taken down and burned.
This story is discounted by modern scholars, but it has become part of the legend of the court of Harun al-Rashid.