Jami` at-Tirmidhi 1681
جامع الترمذي#1681HasanNarrated Ibn 'Abbas: "The flag of the Messenger of Allah (ﷺ) was black, and his standard was white." [Abu 'Eisa said:] This Hadith is Hasan Gharib from this route, as a narration of Ibn 'Abbas
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirHasan
Al-AlbaniHasan
Zubair Ali ZaiHasan
In-book reference: 23:12