Yusuf ibn Firuz (surname also spelled Fayruz) was the Burid governor of Damascus in 1129. He encouraged the massacre of Isma'ili partisans, who were based in the fortress of Banias southwest of Damascus, in September 1129 by Taj al-Mulk Buri . Ibn Firuz was a close adviser of Buri, who replaced him as governor of Damascus. However, when Buri was succeeded by his son Shams al-Mulk Isma'il, the latter tried to have Ibn Firuz killed because he feared that Ibn Firuz was plotting his murder.
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Yusuf ibn Firuz Wikipedia(Text) CC BY-SA