15985
Akhbari 's argue that no Imāms ever allowed Ijtehad and the Door of Ijtehad was opened by Umar ibn al-Khattab .
 Umar ibn al-Khattab
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 ibn al-Khattab