Reference: al-Hifth – Ahammiyyatuhu, ‘Ajaa.ibuhu, Tareeqatuhu, Asbaabuhu – Page 29
al-Hadaa.iq libni-Jowzee – Volume 1, Page 25
Abu Daawood al-Khaffaaf said:
Ishaaq ibn Raahawayh dictated 11,000 hadeeth to us from memory. He then read them (what he had dictated) to us and [found he] had not made a single mistake (in what he had dictated).