Musnad Ahmad 30:464

Abu Kamil narrated to us, Ibrahim narrated to us, Ibn Shihab narrated to us, from al-Agharr and Abu Salamah, from Abu Hurairah. And Ya’qub said: My father narrated to us, from Ibn Shihab, from al-Agharr, from Abu Hurairah—and Ya’qub did not mention Abu Salamah. [Abdullah ibn Ahmad said]: My father said: Yunus narrated it to us, from al-Agharr and Abu Salamah, from Abu Hurairah, from the Messenger of Allah (may Allah bless him and grant him peace), who said: "When it is the day of Friday, there are angels at every door of the mosque, writing down the first [to arrive] then the first. Then, when the Imam sits, they fold the scrolls and come to listen to the Reminder (the sermon)."