مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2203
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated that Ibn 'Abbas (رضي الله عنه) said: The mushrikeen used to part their hair in the middle and the People of the Book used to let their hair fall over their foreheads, and the Messenger of Allah (ﷺ) liked to do the same as the People of the Book - Ya'qoob said: in some matters concerning which he had received no command; Ishaq said: in that concerning which he had received no command - so he let his hair fall over his forehead, then later on he parted it.
Musnad Ahmad 2209Its isnad is saheeh, al-Bukhari (5917) and Muslim (2336)]