Al-Mughni (The Enricher) is widely considered the masterpiece of Islamic jurisprudence ( Fiqh ) within the Hanbali school. Authored by the great scholar (d. 620 AH / 1223 CE), it is a commentary on Al-Kharqi , but it stands alone as an encyclopedia of comparative Fiqh.
You can find various volumes and translations of the work on major digital libraries: al mughni ibn qudamah pdf