Sa'id bin al-Musayyib narrates from Sayyiduna Sahl bin Sa'd (may Allah be pleased with him) that he was present on the occasion when the Messenger of Allah (peace and blessings be upon him) married a man (to a woman) in return for two surahs of the Qur'an which he would teach her.
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5638