As Umar lay thinking about the issue of nominating a successor he fell asleep. In the dream he saw that a man who had laid out the garden was plucking all the ripe and unripe fruit, and gathering it on the ground. He interpreted this dream to mean that he should name the eligible candidates and then leave them to choose one of themselves as the Caliph. Umar accordingly constituted a Committee of six persons to choose the next Caliph out of themselves.
This Committee comprised: Ali b Abu Talib Uthman b Affan Abdur Rahman b Auf Saad b Abi Waqas Zubair b Awwam Talha b Ubaidullah All these persons were among the most eminent companions of the Holy Prophet, whom he had given the tidings of paradise in their lifetime.
"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