I give her to you in marriage for what you have of the Qur'an
Authentic hadithعن سهل بن سعد الساعدي رضي الله عنهما أن رسول الله صلى الله عليه وسلم جاءته امرأة فقالت: إني وَهَبْتُ نفسي لك: فقامت طويلا، فقال رجل: يا رسول الله، زَوِّجْنِيهَا، إن لم يكن لك بها حاجة. فقال: هل عندك من شيء تُصْدِقُهَا؟ فقال: ما عندي إلا إِزَارِي هذا. فقال رسول الله صلى الله عليه وسلم : إِزَارُكَ إن أَعْطَيْتَهَا جلست ولا إِزَارَ لك، فالْتَمِسْ شيئا قال: ما أجد. قال: الْتَمِسْ ولو خَاتَمًا من حَدِيدٍ. فالْتَمَسَ فلم يجد شيئا. فقال رسول الله صلى الله عليه وسلم هل معك شيء من القرآن؟ قال: نعم. فقال رسول الله صلى الله عليه وسلم : زَوَّجْتُكَهَا بما معك من القرآن».
Sahl ibn Sa‘d As-Sā‘idi (may Allah be pleased with him) reported that a woman came to the Messenger of Allah (may Allah's peace and blessings be upon him) and said: "I give myself in marriage to you." The woman stood for a long time. Then a man said: "O Messenger of Allah, marry her to me if you do not want her." He said: "Do you have anything to give her for dowry?" He said: "I have nothing but my lower garment." So the Messenger of Allah (may Allah's peace and blessings be upon him) said: "If you gave her your lower garment, then you would have nothing to wear. Find something else to give her." He said: "I could not find anything." Then he said: "Find anything even if it is an iron ring." So he looked and did not find anything. The Messenger of Allah (may Allah's peace and blessings be upon him) thus, said: "Do you memorize anything of the Qur'an?" He said: 'Yes.' So the Messenger of Allah (may Allah's peace and blessings be upon him) said: "I give her to you in marriage for what you have (memorized) of the Qur'an."
Explanation
The Prophet (may Allah's peace and blessings be upon him) was addressed with certain rulings that are unique for him and do not apply to others. Examples of these rulings include marrying the woman who gives herself to him in marriage without a dowry. One day, a woman came to the Prophet (may Allah's peace and blessings be upon him) and give herself in marriage to him, hoping to be one of his wives. When he looked at the woman and did not feel any desire for her, he did not decline her request to avoid embarrassing her. He just turned away from her. When she sat down, a man said: "O Messenger of Allah, marry her to me if you do not want her." Since the dowry is obligatory in marriage, he said to the man: "Do you have anything to give her as a dowry?" He replied: "I have nothing but my lower garment/" If the man gave her his lower garment, he would have nothing to wear. For this reason, the Prophet (may Allah's peace and blessings be upon him) said to him: "Look for something else even if it is an iron ring." So when he could not find anything, the Prophet asked: "Do you memorize anything of the Qur'an?" The man replied in the affirmative. So the Prophet (may Allah's peace and blessings be upon him) said: "I give her to you in marriage for what you have (memorized) of the Qur'an," i.e. teach her what you memorize and it will be her dowry.
Source · Narrated by Bukhari & Muslim
From the Hadith Encyclopedia (hadeethenc.com).