Reference: Siyar A’laam an-Nubalaa. – Volume 13, Page 54
Abu Ahmad ibn ‘Adee said:
Ismaa’eel [ibn Zayd al-Jarjaanee] would write 90 pages [of knowledge] every night in small/fine writing.
[About this] ath-Thahabee said:
In this manner, it was quite possible for him to have written Saheeh Muslim in a week.