مُسْنَدُ أَحْمَدَ
Musnad Ahmad 4171
Musnad of Abdullah bin Mas'ood
It was narrated that ‘Abdullah (رضي الله عنه) said: I prayed one night with the Messenger of Allah (ﷺ) and he remained standing until I thought of doing something bad. We said: What did you think of doing? He said: I thought of sitting down and leaving the Prophet (ﷺ).
Musnad Ahmad 4199lts isnad is saheeh]