Sahih Bukhari
Fighting for the Cause of Allah (Jihaad)
Volume: 004 / Book Number: 052 / Hadith Number: 295
Narrated Ibn 'Abbas:
A man came to the Prophet and said, "O Allah's Apostle! I have enlisted in the army for such-and-such Ghazwa, and my wife is leaving for Hajj." Allah's Apostle said, "Go back and perform Hajj with your wife."