Shaykh Izz al-Din ibn Abd al-Salam used to borrow al-Muhalla and al-Mujalla by Ibn Hazm and would say, 'I have not seen in the books of Islam, regarding knowledge, the likes of al-Muhalla and al-Mujalla, and the book al-Mughni by Shaykh Muwaffaq al-Din ibn Qudama, in terms of their quality and the verification of what they contain.' It is also reported that he said, 'I was not content with issuing fatwas until I had a copy of al-Mughni.'

Muwaffaq al-Din was born in Jamma'il, from the district of Nablus, in the month of Sha'ban in the year 541 AH. He arrived in Damascus with his family, having emigrated with his kin and relatives at the age of ten. He read the Quran and memorized 'Mukhtasar al-Khiraqi,' and studied under the scholars there. Then, he traveled to Baghdad with his cousin, al-Hafiz Abd al-Ghani ibn Abd al-Wahid ibn Ali al-Maqdisi, in the year 561 AH. They stayed for four years, during which they mastered jurisprudence, hadith, and [the science of] differences (khilaf). They stayed first with Shaykh Abd al-Qadir ibn Abd Allah al-Jili al-Hanbali, then stayed with Ibn al-Jawzi, and later moved to the Ribat al-Na'al, where they studied under Ibn al-Manni. Al-Muwaffaq returned to Baghdad once more in the year 567 AH, accompanied by 'Imad al-Din Abu Ishaq Ibrahim ibn Abd al-Wahid ibn Ali al-Maqdisi, and they stayed for a year. He performed Hajj in the year 573 AH and heard [hadith] in Mecca.

Ibn Rajab reported from Nasih al-Din al-Hanbali that al-Muwaffaq performed Hajj in the year 574 AH, returned with the Iraqi delegation to Baghdad, and resided there for a year, during which he attended the lesson of Ibn al-Manni. He [i.e., Nasih al-Din] said: 'I had entered Baghdad in the year 572 AH, and we all studied under Shaykh Abu al-Fath ibn al-Manni.' Then he returned to Damascus and occupied himself with compiling the book al-Mughni.

In Damascus, al-Muwaffaq held a teaching position at the Mosque of Damascus for a long time. Abu Shama mentions that after the death of his brother, Abu Umar, al-Muwaffaq was the one who led the people in prayer at the Muzaffari Mosque and delivered the Friday sermon when he was present. If he was not present, then his son, Abd Allah ibn Abi Umar [i.e., the son of al-Muwaffaq's brother], was the preacher and the imam of the Hanbali prayer niche (mihrab) at the Mosque of Damascus. Al-Muwaffaq would pray there when he was in the city; and if he went to the mountain, al-'Imad, the brother of Abd al-Ghani, would lead the prayer. After the death of al-'Imad, Abu Sulayman Abd al-Rahman, the son of al-Hafiz Abd al-Ghani, would lead the prayer there whenever al-Muwaffaq was not present.

Ibn Kathir added: 'He used to perform supererogatory prayers between the two night prayers (Maghrib and Isha) near his prayer niche. When he prayed Isha, he would depart to his house in Darb al-Dawla'i at the pavement, taking with him whomever he could of the poor.'