مُسْنَدُ أَحْمَدَ
Musnad Ahmad 1728
The Musnad of Ahlul-Bayt & Hadeeth of al-Hasan bin 'Ali bin Abu Talib
It was narrated from Ibn Sireen that a funeral passed by Ibn "Abbas and al-Hasan bin "Ali; one of them stood up and the other remained seated. The one who stood up said: Do you not know that the Messenger of Allah (ﷺ) stood up (sometimes)? He said: Yes, and he remained seated (sometimes).
Musnad Ahmad 1728Hasan because of corroborating evidence; and its isnad is da