It is narrated from Sayyiduna Abu Umamah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever teaches a servant one verse of the Book of Allah is his mawla (patron). It is not fitting for him to forsake him, nor to prefer himself over him."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7497