Shaikh Abul Qasim Ja'far b. Hasan b. Yahya b. Saeed Hilli is famous as Muhaqqiq Hilli. He must not be confused with Allama Hilli. Muhaqqiq Hilli was Allama's maternal uncle and also his tutor. He has several books on Fiqh, most popular among them are: Sharae, Maarij, Motabar, Al Mukhtasar Al Nafe etc.
Muhaqqiq Hilli studied from the students of the great masters like Ibn Zehra and Ibn Idrees Hilli. Some have erroneously counted him among those who studied directly from these Fuqaha, forgetting that this was not possible because Muhaqqiq Hilli who died in 676 Hijra could not have attended the lessons of Ibn Idress or Ibn Zehra who had died more than 80 years earlier. Most probably, he was trained by his grandfather and later his father.
Muhaqqiq Hilli is acknowledged as the greatest among Fuqaha, and whenever the term 'Muhaqqiq' is used without any qualification, then it refers to him alone. The great philosopher and mathematician, Khwaja Naseer al-Deen Tusi speaks highly of his reminiscence with Muhaqqiq who he met in Hilla, and attended his classes of Fiqh. Muhaqqiq's book 'Sharae' is still a part of curriculum in most of the Hawzas.