Sahih Muslim Book 20, Hadith Number 4628.

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

It has been narrated on the authority of Abu Huraira who said: Allah has undertaken to provide for one who leaves his home (only) to fight for His cause and to affirm the truth of His word; Allah will either admit him to Paradise or will bring him back home from where he had come out, with his reward and booty.