مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2270
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
‘Urwah said to Ibn 'Abbas (رضي الله عنه): How long will you misguide the people, O Ibn 'Abbas? He said: Why are you saying that, O' Urwah? He said: You enjoin us to do ‘Umrah in the months of Hajj when Abu Bakr and ‘Umar forbade that! Ibn 'Abbas said: The Messenger of Allah (ﷺ) did that. 'Urwah said: They [Abu Bakr and 'Umar] followed the Messenger of Allah (ﷺ) more closely and had more knowledge about him than you.
Musnad Ahmad 2277Its isnad is saheeh]