He did not care for the booty
In the battle Ali killed a wealthy Quraish chief Umar b Ubda, but contrary to the Arab custom, he did not mutilate his body, nor take off his costly coat of mail. When asked why he had not taken his valuable coat of mail, Ali said, "The lion who enters the battlefield either kills himself or is killed he does bother about the booty."
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"When a person dies, his works end, except for three: ongoing charity, knowledge that is benefited from, and a righteous child who prays for him."
Prophet Mohammed (PBUH)
"The best of what a man leaves behind are three: a righteous child who supplicates for him, ongoing charity the reward of which reaches him, and knowledge that is acted upon after him."
Sunan Ibn Mājah
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Sahih Bukhari