Ibn Hajar's Supplement to Mizan al-I'tidal

Lisan al-Mizan (The Tongue of the Balance) is Ibn Hajar al-Asqalani's supplement and critical revision of adh-Dhahabi's Mizan al-I'tidal fi Naqd ar-Rijal. Adh-Dhahabi's Mizan al-I'tidal is a monumental biographical dictionary focusing specifically on narrators who were criticized or weakened by the hadith critics — the jarh side of the tradition. It covers both narrators from the six canonical collections and those from the broader hadith literature, providing detailed documentation of the criticisms leveled against thousands of narrators.

Ibn Hajar undertook his supplement for several reasons. First, adh-Dhahabi had produced Mizan al-I'tidal before al-Mizzi completed Tahdhib al-Kamal, which meant that adh-Dhahabi did not have full access to al-Mizzi's comprehensive documentation of narrators in the six collections. Second, adh-Dhahabi's work had omitted some narrators who warranted inclusion. Third, Ibn Hajar found cases where adh-Dhahabi's assessments needed correction or supplementation.

Lisan al-Mizan therefore serves multiple functions. It incorporates narrators that adh-Dhahabi missed. It supplements the entries of narrators adh-Dhahabi included with additional information from sources available to Ibn Hajar but not to adh-Dhahabi. And in cases where Ibn Hajar disagreed with adh-Dhahabi's assessments, he notes his disagreement and provides his own evaluation.

The work is particularly valuable for narrators who fall outside the six canonical collections — scholars and transmitters whose narrations appear in secondary hadith works, legal compendia, Sufi literature, or historical sources. These narrators are not covered by Tahdhib al-Kamal or Taqrib al-Tahdhib, making Lisan al-Mizan the essential reference for their biographical assessment.

Ibn Hajar's work on Lisan al-Mizan reflects his comprehensive approach to the rijal sciences: he was not satisfied with what earlier scholars had documented but sought to produce the most complete and accurate picture possible, correcting errors where he found them and filling gaps wherever material existed. This ambition for completeness, combined with the critical independence that distinguished his scholarship throughout his career, produced a work that is not merely derivative of adh-Dhahabi's Mizan but genuinely advances the state of the art in narrator criticism. Together the two works give scholars the most complete available record of the criticized narrator tradition and the fullest picture of how that tradition evaluated the reliability of the transmitters upon whom the hadith corpus depends.