مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3201
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated that Ibn 'Abbas (رضي الله عنه) said: I was present on Eid with the Prophet (ﷺ), Abu Bakr and ʼUmar, and they started with the prayer before the khutbah.
Musnad Ahmad 3225lts isnad is saheeh, al-Bukhari (979) and Muslim (884)]