BG 6.6-8
The Self is the friend of the self of him in whom the self by the Self is vanquished; but to the unsubdued self the Self verily becometh hostile as an enemy. The higher Self of him who is Self -controlled and peaceful is uniform in cold and heat, pleasure and pain, as well as in honour and dishonour. The Yogî who is satisfied with wisdom and knowledge, unwavering, whose senses are sub dued, to whom a lump of earth, a stone and gold are the same, is said to be harmonised.