After the assassination of Othman, 'Amr b Al-Aas decided to follow a policy of neutrality and watch further developments. When Ali was elected as the Caliph, 'Amr b Al-Aas neither took the oath of allegiance to Ali nor opposed him. 'Amr b Al-Aas had expected that Ali would offer him the governorship of Egypt. If Ali had offered him the governorship of Egypt he would have offered him allegiance. In the absence of such offer 'Amr b Al-Aas decided to remain in Palestine and watch further developments. Ali appointed Qais b Sa'ad as the Governor of Egypt. Qais proved to be a good Governor, and he kept Egypt safe for Ali. Muawiyah succeeded in creating differences between Ali and Qais which culminated in the deposition of Qais. Amr b Al-Aas expected that Ali would in his own interests appoint him as the Governor of Egypt. When Ali appointed Muhammad b Abu Bakr as the Governor of Egypt, 'Amr b Al-Aas despaired of any recognition from Ali. That threw him in the lap of Muawiyah.
"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