Muhammad bin Qasim sent me to Bara bin Azib to ask him about the banner of the Messenger of Allah ﷺ. He said, "It was black, square, and made of a woolen cloth called namira."
بعثني محمد بن القاسم إلى البراء بن عازب أسأله عن راية رسول الله ﷺ فقال: كانت سوداء مربعة من نمرة.
Narrated by Tirmidhi (1680), Abu Dawud (2591), Ahmad (18627), and Bayhaqi (6/363), all of them through the route of Yahya bin Zakariya bin Abu Zaida, who said, our teacher Abu Yaqub Thaqafi narrated to us, our teacher Yunus bin Ubayd narrated to us, and mentioned it.Abu Yaqub Thaqafi is Ishaq bin Ibrahim Kufi. Ibn Adi said in al-Kamil (1/333–334), "He narrated from trustworthy narrators things that no one else corroborates," then said, "his hadiths are not preserved." Ibn Hibban mentioned him in his Thiqat (8/106), which is why Ibn Hajar said, "Ibn Hibban considered him trustworthy, but there is weakness in him."As for Yunus bin Ubayd, no narrator is known to have transmitted from him other than Ishaq bin Ibrahim Thaqafi, and no one has affirmed his reliability except that Ibn Hibban mentioned him in his Thiqat (5/554), which is why Ibn Hajar said, "acceptable," meaning when corroborated, and I have not found any corroboration for him.However, Tirmidhi said in his Ilal al-Kabir (2/713), "I asked Muhammad, meaning Bukhari, about this hadith, and he said, it is a hasan hadith." Tirmidhi said in his Sunan, "This is a hasan gharib hadith, we do not know it except through the hadith of Ibn Abu Zaida." Dhahabi said, in the biographical entry on Yunus bin Ubayd in al-Mizan (4/282), "It is not known who he is. His hadith mentioning the banner of the Prophet ﷺ, that it was black and square, made from a namirah, is a hasan hadith." End of quote. Perhaps those who graded this hadith as hasan looked at the origin of the hadith. As for his word "namirah," it is a woolen cloak with white and black stripes.As for what was narrated from Simak, from a man of his tribe, from another man among them, who said, "I saw the banner of the Messenger of Allah ﷺ, it was yellow," this is daif. It was narrated by Abu Dawud (2593), Ibn Abu Asim in al-Ahad wal-Mathani (1694), and Bayhaqi (6/363), all of them through the route of Salm bin Qutayba, from Shuba, from Simak, with this wording. Its chain of transmission is daif due to the anonymity of Simak bin Harb's teacher, and Munziri faulted it for this reason in his Mukhtasar (3/406).