Yoga Sūtra Chapter Three verse 41

śrotra-ākāśayoḥ saṃbandha-saṃyamāt-divyaṃ śrotram ||41||

From complete restraint of connection between ear and space;
divine hearing.

śrotra - ear, act of hearingākāśa - space; ether; subtle and ethereal fluid; sky, atmospheresaṃbandha - connectionsaṃyama - complete restraintdivya - divine