Surah An Nur - verse 35:
"Allah is the Light of the heavens and the earth. The similitude of His light is as a niche wherein is a lamp. The lamp is in a glass. The glass is as it were a shining star,(This lamp is) kindled from blessed tree, an olive neither of the East nor of the West, whose oil would almost glow forth(of itself) though no fire touched it. Light upon light, Allah guideth unto His light whom He will. And Allah setteth forth for mankind similitudes, for Allah is Knower of all things."