Columbia subject headings:
ʻUmar ibn al-Khaṭṭāb, Caliph, -644.
Harvard subject headings:
Islam and justice
ʻUmar ibn al-Khaṭṭāb, Caliph, -644
Princeton subject headings:
ʻUmar ibn al-Khaṭṭāb, Caliph, -644--Political and social views.