(119) باب الْجَعَائِلِ وَالْحُمْلاَنِ فِي السَّبِيلِ
Narrated Abu Huraira:
Allah's Messenger (ﷺ) said, "Were it not for the fear that it would be difficult for my followers, I would not have remained behind any Sariya, (army-unit) but I don't have riding camels and have no other means of conveyance to carry them on, and it is hard for me that my companions should remain behind me. No doubt I wish I could fight in Allah's Cause and be martyred and come to life again to be martyred and come to life once more."
Reference: Sahih al-Bukhari 2972
In-book reference: Book 56, Hadith 181
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 4, Book 52, Hadith 216