Brahma Sutras
ॐ प्रकाशवच्चावैशेष्यं ॐ ॥ ३-२-२५॥
And the effulgent Self appears to be different during activity, as is the case with light etc.; yet (intrinsically) there is non-difference as is evident from repetition (of “That thou art”).
english translation
OM prakAzavaccAvaizeSyaM OM ॥ 3-2-25॥
hk transliteration by Sanscript