One whose self is steadied in yoga sees the Self abiding in all beings, and all beings in the Self; everywhere, such a person sees with an even eye.
Explanation
Krishna is describing the person who has become established in yoga (union, disciplined meditation), following the joy of contact with Brahman in the previous verse. Such a person sees the Self (ātman) as present in every being and every being as present in the Self, and so views all with equal regard (samadarśana). Advaita readers take this as the oneness of the Self with all, while devotional traditions read it as seeing every being in relation to God; the verse itself leads into Krishna's words about seeing Him everywhere.