Yunus ibn Ubayd, client of Muhammad ibn al-Qasim, said that Muhammad ibn al-Qasim sent to al-Bara' ibn Azib to ask him about the standard of the Messenger of Allah ﷺ. He said: It was black and square, being made of a woollen rug.  

عَنْ رَايَةِ رَسُولِ اللَّهِ ﷺ مَا كَانَتْ فَقَالَ كَانَتْ سَوْدَاءَ مُرَبَّعَةً مِنْ نَمِرَةٍ  

When the Prophet ﷺ entered Mecca his banner was white.  

عَنْ جَابِرٍ يَرْفَعُهُ إِلَى النَّبِيِّ ﷺ أَنَّهُ كَانَ لِوَاؤُهُ يَوْمَ دَخَلَ مَكَّةَ أَبْيَضَ  

Simak reported on the authority of a man from his people, on the authority of another man from them: I saw that the standard of the Messenger of Allah ﷺ was yellow.  

رَأَيْتُ رَايَةَ رَسُولِ اللَّهِ ﷺ صَفْرَاءَ