Oh Arjuna! One who sees all beings with equality by comparison with oneself, whether in pleasure or in pain — is considered the supreme yogi.

Ātmaupamya — comparison/likeness to one’s own ātman. The yogi sees others as themselves: “as I desire sukha and avoid duḥkha, so do others.” This is the ethical foundation of yoga.

This is paramaḥ yogī (the supreme yogi) according to Kṛṣṇa — not one who does spectacular postures, but one who has sama-dṛṣṭi (equal vision) toward all sentient beings.