This is a disconnected report, whereas the version transmitted by Ṣāliḥ Jazara is sounder.

Al-Khaṭīb (1) recorded it from ʿAbd Allāh ibn Aḥmad al-Sūdhrajānī, who said that he heard Ibn Mandah make that statement.

Al-Ḥāfiẓ Abū Aḥmad Ibn ʿAdī said: I heard my father relate, “I was in Rayy, a young apprentice among the cloth-dealers, when a man swore—binding the divorce of his wife—that Abū Zurʿah had memorised one hundred thousand hadith. A group of us, myself included, went to Abū Zurʿah and asked him about it.

He said, ‘What prompted him to take an oath of divorce?’

It was answered, ‘He has just done so.’

Abū Zurʿah replied, ‘Let him keep his wife, for she is not divorced by that oath,’ or words to that effect. (2)

Ibn ʿAdī also said: I heard al-Ḥasan ibn ʿUthmān al-Tustarī say that he heard Abū Zurʿah declare, ‘Every report in which al-Ḥasan (al-Baṣrī) says, “The Messenger of Allah ﷺ said …,” I have traced to an authentic source—except four hadith.’

Ibn Abī Ḥātim reported that Abū Zurʿah remarked, ‘I am astonished at anyone who issues legal opinions on divorce while having memorised fewer than one hundred thousand hadith.’

Ibn Abī Shaybah said, ‘I have never seen anyone with a better memory than Abū Zurʿah.’ (3)

Abū ʿAbd Allāh al-Ḥākim said: I heard Abū Jaʿfar Muḥammad ibn Aḥmad al-Rāzī report that he heard Muḥammad ibn Muslim ibn Wāra say, ‘I was with Isḥāq in Nishapur when a man from Iraq said, “I heard Aḥmad ibn Ḥanbal state: ‘Seven hundred thousand-plus hadith have been authenticated, and this young man’—meaning Abū Zurʿah—‘has memorised six hundred thousand hadith.’” (4)