ʾAḥmad ibn Muḥammad ibn Hārūn ibn Yazīd al Baghdādī (Arabic: أبو بكر الخلال) better known as Abū Bakr al Khalāl, was a Medieval Muslim jurist.^[1]

Al-Khallal was a student of five of Ahmad ibn Hanbal's direct students, including Ibn Hanbal's son Abdullah.^[2] His documentation on Ibn Hanbal's views eventually reached twenty volumes and ultimately led to the preservation of the Hanbali school of Islamic law.^[3] He was considered the principal Hanbalite scholar of his time.^[4]

Al-Khallal's exact date of birth is not known. He died in 923, which means that he would have been born during Ibn Hanbal's twilight years.^[5] The Oxford International Encyclopaedia of Legal History estimates al-Khallal's year of birth as 848.^[1]

Aside from his legal efforts, virtually nothing is known of al-Khallal's life.^[1][2] During his efforts to compile the views of Ibn Hanbal, al-Khallal ended up spending periods of time living in Fars province, Syria and Mesopotamia.^[6] According to Muslim historian Al-Dhahabi, there was no such thing as an independent Hanbalite school of law prior to al-Khallal's efforts at compiling Ibn Hanbal's views.^[6] Al-Khallal's status within the school was not universally accepted, and he and his students were often in conflict with fellow Hanbalite Al-Hasan ibn 'Ali al-Barbahari and his students.^[7]

The historian al-Dhahabi stated that, "Before him (al-Khallal) there were no independent school of the imam's; not until he followed up Ahmad's texts, wrote them down and checked their proofs after 300."^[8]

The 20th century Hanbali jurisprudent Ibn Badran called al-Khallal's collection "the very root of the Hanbali school, from which sprang all later books of Hanbali jurisprudence".^[8]

• Bibliography at Alibris