مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3409
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Ibn ‘Abbas and from Thabit from Anas that The Prophet (ﷺ) used to deliver the khutbah leaning on a palm trunk... And he narrated a similar report.
Musnad Ahmad 3432lts isnad is saheeh]