Sayyiduna Sahl bin Sa'd (may Allah be pleased with him) relates that a woman came to the Prophet (peace and blessings be upon him) and said: O Messenger of Allah, I have come to give myself to you. She stood for a long time while the Prophet (peace and blessings be upon him) did not look at her; then he (peace and blessings be upon him) raised his gaze to her and lowered it again. When her standing had gone on long, she moved aside and sat down. Then a man from the gathering stood up and said: O Messenger of Allah, if you have no need of her, then marry her to me. The Prophet (peace and blessings be upon him) said: "Do you have anything you could give her as dowry (mahr)?" He said: No, by Allah, O Messenger of Allah. He (peace and blessings be upon him) said: "Go and look." He went, then came back and said: No, by Allah, O Messenger of Allah, I did not find anything. He (peace and blessings be upon him) said: "Go and search, even if it is only an iron ring." He went, then came back and said: No, by Allah, I did not find anything, not even an iron ring. The narrator said: He had only a waist-wrap on him, and no upper garment. He said: O Messenger of Allah, this waist-wrap of mine. He (peace and blessings be upon him) said: "Your waist-wrap is such that if you wear it, none of it will be on her, and if she wears it, none of it will be on you." The man moved aside, then got up, and the Prophet (peace and blessings be upon him) saw him leaving. He (peace and blessings be upon him) had him called back and asked: "What do you know of the Qur'an?" He said: Such-and-such surah and such-and-such surah, and he listed several surahs. The Prophet (peace and blessings be upon him) said: "Go, I have given her to you in marriage for what you have of the Qur'an."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5886