Sahih Bukhari Volume 007, Book 062, Hadith Number 063.
Narrated By Sahl bin Sad : While we were sitting in the company of the Prophet a woman came to him and presented herself (for marriage) to him. The Prophet looked at her, lowering his eyes and raising them, but did not give a reply. One of his companions said, "Marry her to me O Allah's Apostle!" The Prophet asked (him), "Have you got anything?" He said, "I have got nothing." The Prophet said, "Not even an iron ring?" He Sad, "Not even an iron ring, but I will tear my garment into two halves and give her one half and keep the other half." The Prophet; said, "No. Do you know some of the Quran (by heart)?" He said, "Yes." The Prophet said, "Go, I have agreed to marry her to you with what you know of the Qur'an (as her Mahr)." 'And for those who have no courses (i.e. they are still immature). (65.4) And the 'Iddat for the girl before puberty is three months (in the above Verse).