Hadithcore
Bulugh al-Maram, 542

Ibn ‘Abbas (RAA) narrated that the Messenger of Allah (ﷺ) said concerning the man who fell off his mount and died during Hajj, “Wash him with water and Sidr (lotus leaves) and shroud him in his two garments (that he was wearing for Ihram).” Agreed upon.

وَعَنِ ابْنِ عَبَّاسٍ رَضِيَ اَللَّهُ عَنْهُمَا: أَنَّ اَلنَّبِيَّ ‏- صلى الله عليه وسلم ‏-قَالَ فِي اَلَّذِي سَقَطَ عَنْ رَاحِلَتِهِ فَمَاتَ: { اغْسِلُوهُ بِمَاءٍ وَسِدْرٍ, وَكَفِّنُوهُ فِي ثَوْبَيْنِ } مُتَّفَقٌ عَلَيْهِ [1]‏ .‏

References2 variants
In-Book Reference
Book 3, Hadith 10
English Reference
Book 3, Hadith 566