مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3819
Musnad of Abdullah bin Mas'ood
It was narrated that 'Abdullah (رضي الله عنه) said: When The Messenger of Allah (ﷺ) died, the Ansar said: A leader from among us and a leader from among you. 'Umar came to them and said: O Ansar, do you not know that the Messenger of Allah (ﷺ) ordered Abu Bakr to lead the people in prayer? They said: Yes indeed. He said: Who among you could feel at ease putting himself ahead of Abu Bakr? They said: We seek refuge with Allah from putting ourselves ahead of Abu Bakr.
Musnad Ahmad 3842lts isnad is hasan]