Anti-Jewish sentiments usually flared up at times of the Muslim political or military weakness or when Muslims felt that some Jews had overstepped the boundary of humiliation prescribed to them by the Islamic law. In Moorish Iberia, ibn Hazm and Abu Ishaq focused their anti-Jewish writings on the latter allegation. This was also the chief motivation behind the 1066 Granada massacre, when "ore than 1,500 Jewish families, numbering 4,000 persons, fell in one day", and in Fez in 1033, when 6,000 Jews were killed. There were further massacres in Fez in 1276 and 1465.