Noun
wajib (countable and uncountable, plural wajibs)
(Islam) A religious duty; something that Muslims are obliged to do.
If, on the other hand, the collector is just in the collection but unjust in the distribution, the concealment of property from him is an obligation (wajib). Source: Internet
When actualized, the contingent becomes a 'necessary existent due to what is other than itself' (wajib al-wujud bi-ghayrihi). Source: Internet