Verse 4 of Sura 66 reads {66:4}: "Now if both of you turn to Allah repentant it will be better for you, as your hearts are already so inclined. But if you back up each other against him, surely Allah is his helper, and Gabriel and the righteous among the believers, and furthermore all other angels too are his helpers".
According to Ibn Abbas, the Holy Prophet said that the "righteous men" alluded to as "helper" in this verse refers to Ali.
"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
"Every day two angels come down from Heaven and one of them says, 'O Allah! Compensate every person who spends in Your Cause,' and the other (angel) says, 'O Allah! Destroy every miser.'"
Sahih Bukhari