Bhagavad Gītā Chapter Six verse 6
bandhur ātmā ’tmanas tasya yenātmāivātmanā jitaḥ |
anātmanas tu śatrutve vartetātmāiva śatruvat ||
citta - psyche (the totality of the human mind, conscious and unconscious); mind; heartātman - essence; the highest personal principle of life; the individual soul, selftasya - its, of it, of thisanātman - other than essenceCommentaries and Reflections