Sahih Bukhari
Good Manners and Form (Al-Adab)
Volume: 008 / Book Number: 073 / Hadith Number: 3
Narrated 'Abdullah bin 'Amr:
A man said to the Prophet, "Shall I participate in Jihad?" The Prophet said, "Are your parents living?" The man said, "Yes." the Prophet said, "Do Jihad for their benefit."