The Holy Quran 2:209, 210O you who have believed, enter into Islam completely [and perfectly] and do not follow the footsteps of Satan. Indeed, he is to you a clear enemy.
But if you deviate after clear proofs have come to you, then know that Allah is Exalted in Might and Wise.
Surat Al-Baqarah (The Cow) - سورة البقرة
The Holy Quran 2:186

Bukhari & Muslim
"O Allah, place light in my heart, light in my tongue, light in my hearing, light in my sight, light behind me, light in front of me, light on my right, light on my left, light above me and light below me; place light in my sinew, in my flesh, in my blood, in my hair and in my skin; place light in my soul and make light abundant for me; make me light and grant me light."