He who, through the likeness (sameness) of the Self, O Arjuna, sees equality everywhere, be it pleasure or pain, he is regarded as the highest YOGI.

ātmā = with his self; aupamyena = by comparison; sarvatra = everywhere; samaṃ = equally; paśyati = sees; yaḥ = he who; arjuna = O Arjuna; sukhaṃ = happiness; vā = or; yadi = if; vā = or; duḥkhaṃ = distress; saḥ = such; yogī = a transcendentalist; paramaḥ = perfect; mataḥ = is considered.;