It wasnarrated that Harith bin Hassan said:
"I came to Al-Madinahand sawthe Prophet (ﷺ) standing on the pulpit, and Bilal standingin frontof him, with his sword by his side, and (I saw) a black flag.I said:'Who is this?' He said: 'This is 'Amr bin 'As, who has justcome back from a campaign.'"
English reference: Vol. 4, Book 24, Hadith 2816
Arabic reference: Book 24, Hadith 2923