When the Muslims arrived in Madinah, there was a serious problem. The city had only one main well of sweet drinking water, the Well of Rumah. It was owned by a man from the Banu Ghifar tribe who sold water to people by the bucket.
The Muslims could not afford to keep paying. Many went thirsty.
The Prophet ﷺ stood before his companions and said:
"Who will buy the Well of Rumah and make it available for all Muslims, and in return he will have something better than it in paradise?"
Uthman (ra) went to the owner the very next day. The man refused to sell the well entirely. So Uthman offered something unusual: he would buy half the well. The two would share it, taking turns, one day for Uthman, one day for the owner.
The owner agreed. From his day, Uthman gave the water freely to every Muslim for free. Soon, no one came to the owner's day anymore, because why pay when the next day was free? The owner had no choice but to sell the other half too.
Uthman bought it, and the Well of Rumah became free for all Muslims forever. (Sunan al-Tirmidhi 3701)
مَّن ذَا ٱلَّذِى يُقْرِضُ ٱللَّهَ قَرْضًا حَسَنًۭا فَيُضَٰعِفَهُۥ لَهُۥٓ أَضْعَافًۭا كَثِيرَةًۭ ۚ وَٱللَّهُ يَقْبِضُ وَيَبْصُۜطُ وَإِلَيْهِ تُرْجَعُونَ
"Who is it that will lend Allah a goodly loan so He may multiply it for him many times over? And Allah withholds and grants abundance, and to Him you will be returned."
Qur'an 2:245Allah asks: who will give a good loan to Allah, meaning, who will spend in His path, so that Allah can multiply it back to them many times over? Uthman answered this call in the most generous way, buying the Well of Rumah and giving free water to all the Muslims. Whatever we give for the sake of Allah, He multiplies and returns to us in ways far greater than we can imagine.