Abu Hazim narrates from Sayyiduna Sahl bin Sa'd al-Sa'idi (may Allah be pleased with him) that a woman came to the Prophet (peace and blessings be upon him) and said: "I have gifted myself to you." She remained standing for a long time, so a man stood up and said: "O Messenger of Allah! If you have no need of her, marry her to me." The Messenger of Allah (peace and blessings be upon him) asked: "Do you have anything to give her as a dowry?" He said: "Only this waist-wrapper of mine." He (peace and blessings be upon him) said: "If you give her the waist-wrapper, you will be left without a waist-wrapper; look for something." He said: "I have nothing at all." He (peace and blessings be upon him) said: "Look for something, even an iron ring." Despite searching he found nothing, so the Messenger of Allah (peace and blessings be upon him) said: "Do you know any of the Qur'an?" He said: "I know such-and-such surahs," and he named them. The Messenger of Allah (peace and blessings be upon him) said: "I have married you to her for what you know of the Qur'an."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصداق / 14398