Sa'ad b Abi Waqas belonged to the section of the Quraish to which the mother of the Holy Prophet belonged. Sa'ad became a convert to Islam at the age of seventeen. He participated in all the expeditions undertaken by the Holy Prophet. He had the distinction for shooting the first arrow in the cause of Islam. He was the only person to whom the Holy Prophet said, "May my parents be your ransom". He was very close to the Holy Prophet. The Holy Prophet held him in high esteem. He was one of the ten distinguished Muslims, whom the Holy Prophet gave 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