"Oh! Messenger of Allah! I do not have a husband and I want to be a good wife; i give myself to you."
The Messenger of Allah [PBUH] kept silent for a long while.
Suddenly, a man who was present stood up and asked if the woman would accept him for a husband.
The Messenger of Allah [PBUH] said: "Do you have anything to give her as a dowry."
The man thought and said: "I have half of my cloth," and indeed he was wearing a single cloth around him.
"If you give her part of this cloth, you will have nothing to wear anymore; it will become her possession. Find something else." Since at this time the followers of Islam and the Prophet himself [PBUH] were poor, the man thought again a long time and declared: "No, I do not possess a thing to give her."
The Messenger of Allah then told him: "Go to your house and look for something, even if it is an iron ring."
The man departed and came back a while later, and declared: "I looked everywhere, but I did not find anything to give her as her dowry."
After reflection, the Prophet of Allah [PBUH]said: "Did you learn some of the Qur'an?"
"Yes, I have learned by heart so-and-so Surahs [chapters of the Qur'an]"
The Messenger of Alah [PBUH] therefore declared: "Teach her what you know of the Qur'an, and this will constitute her dowry."
The couple felt contented with what was proposed, and they got married.
Source: muslim foundation