Sahih Muslim Book 20, Hadith Number 4631.

Chapter : The merit of Jihad and campaigning in the way of Allah.

It has been narrated on the authority of Abu Huraira who said: I heard the Messenger of Allah (may peace be upon him) say: I would not stay behind (when) an expedition (for Jihad was being mobilised) if it were going to be too hard upon the believers… This is followed by the same words as have appeared in the previous tradition, but this tradition has the same ending as the previous hadith with a slight difference in the wording: “By the Being in Whose Hand is my life, I love that I should be killed in the way of Allah; then I should be brought back to life and be killed again in His way…”