Fighting for the Cause of Allah (Jihaad)

Bukhari :: Book 4 :: Volume 52 :: Hadith 248

Narrated 'Abdullah bin 'Amr:

A man came to the Prophet asking his permission to take part in Jihad. The Prophet asked him, "Are your parents alive?" He replied in the affirmative. The Prophet said to him, "Then exert yourself in their service."