Musnad Ahmad 938:27

Ya'qub narrated to us, my father narrated to us, from Salih. Ibn Shihab said: Sahl ibn Sa'd al-Sa'idi narrated to me, that he said: I saw Marwan ibn al-Hakam sitting in the mosque, so I approached until I sat by his side. He informed us that Zayd ibn Thabit informed him that the Messenger of Allah, peace and blessings of Allah be upon him, dictated to him: "Not equal are those who sit" [An-Nisa: 95]. Then he mentioned the hadith.