Here is the Sanskrit anuvad, Hindi anuvad, and English translation of Ksetra-Ksetrajna-Vibhaga Yoga Chapter 13, Verse 13.18.
Sanskrit
ज्योतिषामपि तज्ज्योतिस्तमसः परमुच्यते । ज्ञानं ज्ञेयं ज्ञानगम्यं हृदि सर्वस्य विष्ठितम् ॥ १३.१८ ॥
Hindi
वह परब्रह्म ज्योतियोंका भी ज्योति एवं मायासे अत्यन्त परे कहा जाता है । वह परमात्मा बोधस्वरूप, जाननेके योग्य एवं तत्त्वज्ञानसे प्राप्त करनेयोग्य है और सबके हृदयमें विशेषरूपसे स्थित है|
English
He is light of all lights and is said to be beyond darkness. He is Knowledge, the Knowable (that which has to be known) and the goal of Knowledge, and He is seated in the hearts of all.