The death of Murad was immediately avenged upon the battle-field by the execution of the prisoners of noble birth. Practically all the Serbian aristocracy that had remained loyal to Lazar and the national cause perished. In the midst of this bloody work, Bayezid sent servants to seek out his brother Yakub, who had distinguished himself during the battle, and was being acclaimed by his soldiers. Yakub was taken to Bayezid’s tent, and strangled with a bowstring.[428] The new emir justified this crime by a verse conveniently found for him by his theologians in the Koran: ‘So often as they return to sedition, they shall be subverted therein; and if they depart not from you, and offer you peace and restrain their hands from warring against you, take them and kill them wheresoever ye find them.’[429] They declared that the temptation to treason and revolt was always present in the brothers of the ruler, and that murder was better than sedition. These doctors of the law might better have pointed out to Bayezid the admonition of the Prophet: ‘But his soul suffered him to slay his brother, and he slew him: wherefore he became of the number of those who perish.’[430] For the abominable practice of removing possible rival claimants by assassination, thus begun on the field of Kossova, was elevated to the dignity of a law by Mohammed II,[431] and has been until our own times a blot upon the house of Osman. Bayezid, however, was only following the example of Christian princes of his own century. Pedro of Castille killed his brother Don Fadrique;[432] Andronicus III Comnenos of Trebizond, killed his two brothers, Michael and George;[433] and Andronicus III Palaeologos assassinated his brother when his father was dying.[434] An order was issued from the battle-field of Kossova to the Kadi of Brusa, enjoining him to keep secret the death of Murad, and to appear to be occupied only with public rejoicing for the victory ‘won from the _Hungarians_’. With this order, Bayezid forwarded the bodies of his father and brother for secret burial at Brusa.[435]