Allah the Almighty recounted this story: And tell them about the guests (angels) of Abraham. When they entered unto him, and said: "Salaaman (peace)!" (Abraham) said: "Indeed! We are afraid of you."
They (the angels) said: "Do not be afraid! We give you glad tidings of a boy (son) possessing much knowledge and wisdom." (Abraham) said: "Do you give me glad tidings (of a son) when old age has overtaken me? Of what then is your news?" They (the angels) said: "We give you glad tidings in truth. So be not of the despairing." (Abraham) said: "And who despairs of the Mercy of his Lord except those who are astray?" (Abraham again) said: "What then is the business on which you have come, 0 Messengers?"
They (the angels) said: "We have been sent to a people who are Mujrimeen (criminals, disbelievers polytheists, sinners). (All) except the family of Lot. Them all we are surely going to save (from destruction)."
Except his wife, of whom We have decreed that she shall be of those who remain behind (i.e. she will be destroyed).
"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