Bg 15.17

uttamah purusas tv anyah
paramatmety udahrtah
yo loka-trayam avisya
bibharty avyaya isvarah

Word for word: 
uttamah — the best; purusah — personality; tu — but; anyah — another; parama-atma — the Supreme Self; iti — thus; udahrtah — is said; yah — who; loka — of the universe; trayam — the three divisions; avisya — entering; bibharti — is maintaining; avyayah — inexhaustible; isvarah — the Lord.

Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Besides these two, there is the greatest living personality, the Supreme Soul, the imperishable Lord Himself, who has entered the three worlds and is maintaining them.

Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The idea of this verse is very nicely expressed in the Katha Upanisad (2.2.13) and Svetasvatara Upanisad (6.13). It is clearly stated there that above the innumerable living entities, some of whom are conditioned and some of whom are liberated, there is the Supreme Personality, who is Paramatma. The Upanisadic verse runs as follows: nityo nityanam cetanas cetananam. The purport is that amongst all the living entities, both conditioned and liberated, there is one supreme living personality, the Supreme Personality of Godhead, who maintains them and gives them all the facility of enjoyment according to different work. That Supreme Personality of Godhead is situated in everyone’s heart as Paramatma. A wise man who can understand Him is eligible to attain perfect peace, not others.