مُسْنَدُ أَحْمَدَ
Musnad Ahmad 1997
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) would fast until we thought that he would never break his fast, and he would not fast until we thought that he would never fast. And he never fasted any month in full since he came to Madinah except Ramadan.
Musnad Ahmad 1998Sahih (Darussalam) []