Musannaf Ibn Abi Shayba 21:349

Marhum ibn Abd al-Aziz narrated to us, from Abu Na'amah al-Sa'di, from Abu Uthman al-Nahdi, from Abu Sa'id al-Khudri, who said: Mu'awiyah went out to a circle in the mosque and said, "What has made you sit?" They said, "We sat to remember Allah and praise Him for guiding us to Islam and bestowing it upon us." He said, "By Allah, nothing has made you sit except that?" They said, "By Allah, nothing has made us sit except that." He said, "Verily, I did not ask you to swear out of suspicion of you, and there is no one who was in the position of the Messenger of Allah (may Allah bless him and grant him peace) who has narrated fewer hadiths from him than I. The Messenger of Allah (may Allah bless him and grant him peace) went out to a circle of his companions and said, 'What has made you sit?' They said, 'We sat to remember Allah and praise Him for guiding us to Islam and bestowing it upon us.' He said, 'By Allah, nothing has made you sit except that?' They said, 'By Allah, nothing has made us sit except that.' He said, 'Verily, I did not ask you to swear out of suspicion of you, but Jibril came to me and informed me that Allah is boasting of you to the angels.'"