It is reported from Sayyiduna Abu al-Darda' (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever takes a bow for teaching the Qur'an, Allah will collar him with a bow of fire."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الإجارة / 11685