All of us recognize the importance of the Musnad of Imām Aḥmad within the hadith canon. Al-Ḥāfiẓ al-Dhahabī even prayed that God would appoint someone to arrange and serve this Musnad. God answered that prayer through the righteous, devout scholar Shaykh Abū Bakr ibn ʿAbd Allāh al-Muḥibb al-Ṣāmit. He organized it alphabetically by the Companions, ordered the narrations the way the books of aṭrāf do, and expended great effort on it.
Later, the eminent scholar—historian of Islam and ḥadith master of Syria—ʿImād al-Dīn Abū al-Fidāʾ Ismāʿīl ibn ʿUmar ibn Kathīr (may Allah have mercy on him) obtained this arranged copy from its compiler. He supplemented it with the aḥādīth of the Six Books, al-Ṭabarānī’s Muʿjam al-Kabīr, the Musnad of al-Bazzār, and the Musnad of Abū Yaʿlā al-Mawṣilī. He taxed himself severely and toiled immensely over it, producing a work for which no equal exists in the world (1).
Al-Ḥāfiẓ Ibn Kathīr, moreover, knew the Musnad by heart.
The working method therefore became clear to him: extract the Musnad of Imām Aḥmad in light of Tuḥfat al-Ashrāf; do the same with al-Ṭabarānī’s Muʿjam al-Kabīr—already arranged by Companion—then add the Musnad of al-Bazzār as material absent from the Six Books, together with the Musnad of Abū Yaʿlā al-Mawṣilī. All of this was to be cast in the mould of the Companions’ names, with Ibn al-Athīr’s Asad al-Ghābah serving as the principal framework.
[9 — Al-Takmīl fī Maʿrifat al-Thiqāt wa-l-Ḍuʿafāʾ wa-l-Majhūlīn]
Many of Ibn Kathīr’s biographers agree that the book’s title is al-Takmīl. Ibn Kathīr himself mentions it in al-Bidāya wa-l-Nihāya (8/150; 9/41; 10/41, 76, 106, 108, 117, 197, 313; and 11/257, 277).
Ḥājjī Khalīfah in Kashf al-Ẓunūn and al-Baghdādī in Hadiyyat al-ʿĀrifīn list it under the title “al-Takmila fī Maʿrifat al-Thiqāt wa-l-Ḍuʿafāʾ” (2).
Al-Ḥusaynī says in the supplement to Tadhkirat al-Ḥuffāẓ: “Among his works is al-Takmīl fī Maʿrifat al-Thiqāt wa-l-Ḍuʿafāʾ wa-l-Majhūlīn, in which he combined the material of al-Tahdhīb—Tahdhīb al-Kamāl by al-Mizzī—and al-Mīzān—Mīzān al-Iʿtidāl by al-Dhahabī. It comprises five volumes” (3).
Ibn al-ʿImād states in Shadharāt al-Dhahab: “He abridged Tahdhīb al-Kamāl and added to it what came later in…"