Out of compassion for them I, who dwell within their heart, destroy the darkness born of ignorance by the shining lamp of knowledge.
Out of compassion I destroy the darkness of their ignorance. From within them I light the lamp of wisdom and dispel all darkness from their lives.
The one who sees the imperishable Supreme Lord dwelling equally within all perishable beings truly sees.
Those who practice severe austerities without following the scriptures, with hypocrisy and egotism, impelled by lust, and attachment; / Senselessly torturing the elements in their body and also Me who dwell within the body; know these ignorant persons to be of demonic nature.
This Supreme abode, O Arjuna, is attainable by unswerving devotion to Me within which all beings exist, and by which all this universe is pervaded.
Verily there is no purifier in this world like knowledge. One who becomes purified by Karma-yoga discovers this knowledge within (naturally) in course of time. (See also 4.31, and 5.06).
The embodied one within the body of everyone, O Bharata, is ever undestroyable. Therefore you should not grieve for any being.