مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2917
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 on a reed mat.
Musnad Ahmad 2940Saheeh because of corroborating evidences]