Sayyiduna Sahl bin Sa'd (may Allah be pleased with him) says: I was with the people in the presence of the Messenger of Allah (peace and blessings be upon him). He mentioned this story but did not mention the lower garment, and he said: A man stood up and said: Marry her to me. At its end it says that he (peace and blessings be upon him) said: "I have married her to you in return for what you have of the Qur'an."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13819