Uthman held the following four things as essential: To associate with the worthy is laudable, but to follow them is essential. To read the Holy Quran is virtue, but to act according to its injunctions is essential. To visit the sick is meritorious, but to cause them to make their behests is essential, To visit the shrines of holy men is piety, but to be prepared for death is essential.
"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