 As a consequence for assisting Zangi , the Abbasid authorities sought punitive measures against Ayyub . Simultaneously , in a separate incident , Shirkuh killed a close confidant of Bihruz on charges that he had sexually assaulted a woman in Tikrit . The Abbasid court issued arrest warrants for both Ayyub and Shirkuh , but before the brothers could be arrested , they departed Tikrit for Mosul in 1138 . When they arrived in Mosul , Zangi provided them with all the facilities they needed and he recruited the two brothers into his service . Ayyub was made commander of Ba 'albek and Shirkuh entered the service of Zangi 's son , Nur ad @-@ Din . According to historian Abdul Ali , it was under the care and patronage of Zangi that the Ayyubid family rose into prominence . 
