Fighting for the Cause of Allah (Jihaad)
Bukhari :: Book 4 :: Volume 52 :: Hadith 206
Narrated 'Abdullah bin Zaid:
that in the time (of the battle) of Al-Harra a person came to him and said, "Ibn Hanzala is taking the pledge of allegiance from the people for death." He said, "I will never give a pledge of allegiance for such a thing to anyone after Allah's Apostle."