مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3848
Musnad of Abdullah bin Mas'ood
It was narrated that ‘Amr bin al-Harith bin Abi Dirar al-Khuza'i said: I heard 'Abdullah bin Mas'ood (رضي الله عنه) say: I did not fast twenty-nine days with the Messenger of Allah (ﷺ) more often that I fasted thirty days with him.
Musnad Ahmad 3871Hasan because of corroborating evidence; this is a da’eef is