al-Muhalla by Imam ibn Hazm

Al-Muhalla is one of the largest existing structures, adh-Dhahabi on behalf of the 3 books that have most marked with Sunan al-Kubra al-Bayhaqi and at Tamhid ibn AbdelBarr.

This book is a wealth of scholarship, in which Ibn Hazm discusses each question separately. On each question, he cites the views of earlier scholars of high achievement, not restricting himself to the views of the four schools of Fiqh, but also citing the rulings of scholars like al-Hassan al-Basri (d. 110), al-Laith ibn Saad (d. 175), Ata' (d. 114), Sufyan al-Thawri (d. 161), al-Awza'ie (d. 157), etc. He also quotes the evidence they cite in support of their views. He then discusses why he considers their views incorrect, and produces the evidence in support of his own view. This makes for a highly scholarly discussion. Many scholars describe Al-Muhalla as the encyclopedia of Islamic Fiqh. Indeed, it has preserved many of the views of early scholars whose work was either not documented or lost. The only problem with Al-Muhalla is that Ibn Hazm is often scathing in his criticism of his opponents. Yet there is no doubt that he is an honest defender of what he considers to be the truth.[1]
 
However, this book is a must-Islamic Fiqh, for a public knowledgeable or advanced.

[1] Adil Salahi from muslimheritage.com