Sahih Bukhari Volume 4, Book 52, Hadith Number 54.

Narated By Abu Huraira : The Prophet said, “By Him in Whose Hands my life is! Were it not for some men amongst the believers who dislike to be left behind me and whom I cannot provide with means of conveyance, I would certainly never remain behind any Sariya’ (army-unit) setting out in Allah’s Cause. By Him in Whose Hands my life is! I would love to be martyred in Al1ah’s Cause and then get resurrected and then get martyred, and then get resurrected again and then get martyred and then get resurrected again and then get martyred.