What is the position of fulfilment of promises in Islam?

Hadith is the _____ source of Islamic law?

According to Hadith No. 7 of Al- Nawawi's collections, religion is sincerity to the following except

Anas who related Hadith No. 13 of al-Nawawi's collections was a __________ to the Prophet (SAW)

Actions shall be judged according to intentions is Hadith ______ of al-Nawawi's collections.