Al-Dhahabī’s mastery of critical evaluation and verification stands out in many of his condensations. A striking example is his abridgement of Al-Mustadrak ʿalā al-Ṣaḥīḥayn by Abū ʿAbd Allāh al-Ḥākim al-Naysābūrī (d. 405 AH), a work whose author intended to compile reports that met the conditions of al-Bukhārī and Muslim yet do not appear in their two Ṣaḥīḥs. From a close reading of the epitome—together with al-Dhahabī’s annotations, source identifications, and critiques—it becomes clear that he judged only one half of the book’s narrations to be authentic. Of the remaining half, he held that one further quarter possesses sound isnāds, though each contains some defect, while the final quarter consists of anomalous or very weak reports that are unacceptable; indeed, a number of them are outright fabrications. (1)

This demonstrates that al-Dhahabī re-examined every hadith in Al-Mustadrak and subjected them all to fresh scrutiny before issuing his verdict.

Al-Dhahabī would also habitually trace and document the chains of transmission for the reports found in the works he abridged. Most of the source citations in his Talkhīṣ al-ʿIlal al-Mutanāhiya fī al-Aḥādīth al-Wāhiya—produced from Ibn al-Jawzī’s (d. 597 AH) al-ʿIlal—are, in fact, his own. (2)

When he condensed al-Bayhaqī’s (d. 458 AH) al-Sunan al-Kubrā, he offered valuable comments on its isnāds that testify to his deep command of the discipline. He devised symbols to indicate which reports were also narrated by the two Ṣaḥīḥ compilers or by the authors of the four Sunan, and he provided documentation for the reports absent from these six canonical collections.

Al-Dhahabī likewise often supplied biographical entries for the transmitters mentioned in the books he abridged, drawing upon the science of narrator criticism.