26804
At least some of the clauses of the pact mirror the measures first introduced by the Umayyad caliph Umar II or by the early Abbasid caliphs .
 Umar II, Abbasid
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Umar II, Abbasid