Abu Bakr bin Muhammad bin Amr bin Hazm (may Allah have mercy on him) reports from his grandfather (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) wrote a letter to the people of Yemen in which the obligatory duties, the Sunnahs and the blood-monies (diyat) were mentioned, and he sent Amr bin Hazm (may Allah be pleased with him) with these rulings. In it is: "No one should touch the Qur'an except one who is pure." Others besides him have narrated it as mursal. Allah knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحيض / 1478