From the Quran ofcourse.
I like these two:
” Allah is the Light of the heavens and the earth. The example of His light is like a niche within which is a lamp, the lamp is within glass, the glass as if it were a pearly [white] star lit from [the oil of] a blessed olive tree, neither of the east nor of the west, whose oil would almost glow even if untouched by fire. Light upon light. Allah guides to His light whom He wills. And Allah presents examples for the people, and Allah is Knowing of all things.
(24:35)”
And this
” Or [they are] like darknesses within an unfathomable sea which is covered by waves, upon which are waves, over which are clouds – darknesses, some of them upon others. When one puts out his hand [therein], he can hardly see it. And he to whom Allah has not granted light – for him there is no light.
(24:40)”
Surah nur is one of the prettiest in my opinion.