Uthman already well known for his generosity stepped up his beneficent activities. He financed the project for the construction of the Prophet's mosque in Madina.
In Madina, the Muslims faced the problem of water supply. Most of the wells in Madina had brackish water supply. There was only one well of sweet water in the town namely Beer Rauma. It belonged to a Jew, and he did not allow free access to the Muslims. One day in the Prophet's mosque at Madina the Muslims brought their difficulty to the notice of the Holy Prophet. Thereupon addressing the congregation the Holy Prophet said, "O ye Muslims, who among you would like to purchase the Beer Rauma for the Muslims in return for a home in paradise. Uthman purchased the well for ten thousand dirhams and dedicated it to the free use of the Muslims. Pleased with this beneficent act of Uthman, the Holy Prophet gave him the tiding of paradise in the world to come.
"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