مُسْنَدُ أَحْمَدَ
Musnad Ahmad 4160
Musnad of Abdullah bin Mas'ood
It was narrated from 'Abdullah that he said: I was told of your gathering, but I was kept from coming out to you by fear of boring you. The Messenger of Allah (ﷺ) used to choose the right days to exhort us, for fear of boring us.
Musnad Ahmad 4188Its isnad is saheeh, al-Bukhari (68) and Muslim (2821)]