The Well of 'Uthmān ibn ʿAffān (RA).
When the Muslim community first migrated to Madinah, fresh water was scarce. A single well — Bi'r Rūma — was owned by a man who sold water to the people at a price few could afford.
The Prophet Muhammad ﷺ said, "Whoever buys the well of Rūma and makes it free for the Muslims will have Paradise." 'Uthmān ibn ʿAffān (RA) purchased the well — first a share, then the whole — and dedicated it as a waqf for the community. From that day forward, anyone could drink from it freely.
The well still exists today, more than 1,400 years later. The surrounding land was eventually turned into a date-palm orchard whose proceeds continue to fund public welfare in Madinah. A single act of generosity — still flowing.
"We invest today. They heal tomorrow." — this is the same logic, translated into the language of modern medical training.