It was finally agreed that Nasir should go back to Cairo and murder the wazir. He, as an inmate of the house, would be the best able to get into his presence and do the deed without premature discovery. So the army remained at Bilbays and Nasir returned. The wazir’s house was guarded, but Nasir was well aware of the minister’s habits and went direct to the harim which was in a detached building. He had brought a small body of men with him, and together they went through the grounds to the harim, where Nasir found the wazir asleep and murdered him. As soon as the guards learned what had happened they broke out in disorder and began to search for the assassins, but Nasir and his men had made good their escape, and the household guards seem to have lacked any one to direct their plans, now the master was dead. This murder took place on the 6th of Muharram, 548. As soon as the news was brought to ʿAbbas he returned with his forces to Cairo where he soon restored order, and was without delay invested with the office of wazir. The change does not seem to have aroused any other feelings than relief amongst the people at large, for Ibn as-Sallar had been a harsh and cruel ruler, and many had suffered for suspected partisanship with the defeated Ibn Masal. Early in his period of office he had suppressed the Khalif’s bodyguard of young men, and put most of them to death, and this had been the inauguration of an almost constant series of executions. Thus ʿAbbas was made wazir, but this appointment resulted in the Khalif’s own assassination within the next few months. In the circumstances which led to this it is clear that the chief factor was a close friendship between the Khalif and the wazir’s son Nasir, and with this was the evil influence of Osama. It is said that the Khalif made overtures to Nasir to slay his father ʿAbbas, presumably intending to make the son wazir in his place; but the details of this are obscure and seem to be very much open to question. It is, however, clear that Osama took a leading part in stirring up the feelings of ʿAbbas and his son and inducing them to proceed to this murder, and it is he who definitely states that the Khalif had made overtures to Nasir to assassinate his father, and it seems likely that he says this to excuse his own bad advice.