Abu Sa'id Al-Khudri (May Allah be pleased with him) reported

Mu'awiyah (May Allah be pleased with him) came to an assembly in the mosque and asked them: "What has made you sit together?" They replied, "We are sitting here to remember Allah." He said, "I adjure you by Allah to tell me whether nothing else has made you to sit together." They replied: "By Allah! We are sitting only to remember Allah." Then he said, "I did not adjure you because I suspected you. No one of my rank in the eyes of the Messenger of Allah (ﷺ) is the narrator of so few traditions as I am. The fact is that the Messenger of Allah (ﷺ) went out to a circle of his Companions and said, 'What has made you sit there?' When they replied that they are sitting together to remember Allah and to praise Him for guiding them to Islam and bestowing favours on them, he (ﷺ) said, 'I adjure you by Allah to tell me that nothing else has made you sit together.' On their reply that there was certainly no other purpose, he (ﷺ) said, 'I did not adjure you because I suspected you, but Jibril (Gabriel) came to me and told me that Allah was talking proudly of you to the angels."'

[Muslim].