Asal narrates from Ata (may Allah have mercy on him) that a man married a woman in return for teaching her the Qur'an. The matter was brought before the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) said: "It is permissible."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصداق / 14401