Narrated Rafi' ibn Amr al-Muzani:I saw the Messenger of Allah (ﷺ) addressing the people at Mina (on the day of sacrifice) when the sun rose high (i.e. in the forenoon) on a white mule, and Ali (Allah be pleased with him) was interpreting on his behalf; some people were standing and some sitting.
حَدَّثَنَا عَبْدُ الْوَهَّابِ بْنُ عَبْدِ الرَّحِيمِ الدِّمَشْقِيُّ، حَدَّثَنَا مَرْوَانُ، عَنْ هِلاَلِ بْنِ عَامِرٍ الْمُزَنِيِّ، حَدَّثَنِي رَافِعُ بْنُ عَمْرٍو الْمُزَنِيُّ، قَالَ رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَخْطُبُ النَّاسَ بِمِنًى حِينَ ارْتَفَعَ الضُّحَى عَلَى بَغْلَةٍ شَهْبَاءَ وَعَلِيٌّ - رضى الله عنه - يُعَبِّرُ عَنْهُ وَالنَّاسُ بَيْنَ قَاعِدٍ وَقَائِمٍ .
AbuDaud
The Rites of Hajj (Kitab Al-Manasik Wa'l-Hajj) • Hadith 1956