After the death of the Holy Prophet when his body was still to be buried, the Ansars met at Saqifa Bani Sauda to urge that the successor to the Holy Prophet should be chosen out of them. When the Muhajireen came to know of this gathering, Abu Bakr, Umar, and some other Quraish leaders attended the meeting. The Ansars demanded that the Caliph should be elected out of them. When the Quraish made a counter claim, the Ansars suggested that one Amir be elected from among the Ansars, and another Amir from among the Muhajireen. The Muhajireen contended that such dual caliphate would lead to disunity in the ranks of the Muslims which would be against the interests of Islam. After a good deal of discussion, the Ansars gave way and Abu Bakr from among the Muhajireen was elected as the Caliph.
"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