مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2981
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated that Ibn 'Abbas (رضي الله عنه) said: The Messenger of Allah (ﷺ) used to pray eight rak’ahs at night and pray Witr with three, and he would pray two rak'ahs of Fair.
Musnad Ahmad 3004Saheeh]