مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3823
Musnad of Abdullah bin Mas'ood
It was narrated that 'Abdullah (رضي الله عنه) said: I learned seventy soorahs from the lips of the Messenger of Allah (ﷺ) when Zaid bin Thabit was still a boy with braided hair, learning to read and write.
Musnad Ahmad 3846A saheeh hadeeth, al-Bukhari (5000) and Muslim (2462) and it