Sunan an-Nasa'i 3008
It was narrated from Salamah bin Nubait that his father said:
"I saw the Messenger of Allah delivering a Khutbah on the day of Arafat atop a red camel." (Hasan)
Chpater 200. Delivering A Short Khutbah In 'Arafat
أَخْبَرَنَا مُحَمَّدُ بْنُ آدَمَ، عَنِ ابْنِ الْمُبَارَكِ، عَنْ سَلَمَةَ بْنِ نُبَيْطٍ، عَنْ أَبِيهِ، قَالَ رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَخْطُبُ يَوْمَ عَرَفَةَ عَلَى جَمَلٍ أَحْمَرَ ‏.‏