Musannaf Ibn Abi Shaybah

Hazrat Dawood bin Shaboor narrates that Hazrat Mujahid said: I used to take pride among the people for being a firm memorizer of the Qur'an, until I prayed behind Hazrat Muslamah bin Makhlad. Then he began Surah Al-Baqarah and did not make a single mistake, not even in an alif or a waw.