When Umar passed away, Ali mourned his death in the following terms: "May God bless the soul of Umar. He made things straight. He cured the malady. He enforced the Shari'ah. He established law and order. He was noble, virtuous, and free from faults. He availed of what was good of the caliphate and avoided what was evil thereof. He obeyed God, and served His cause well. After his passing away the people have taken to different paths where those who have strayed cannot find the way, and those who have followed the straight way cannot long keep it."
"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