Take refuge in him alone, with your whole being, O descendant of Bharata. By his grace you will reach supreme peace and the eternal abode.
Explanation
Krishna has just said that the Lord (Īśvara) dwells in the heart of every being. Here he tells Arjuna to surrender to that Lord completely, with his whole being (sarva-bhāva). Grace (prasāda) brings supreme peace (śānti) and the eternal state. Traditions differ on who "him" is: some Vedanta readings take it as the inner Self or Brahman, while devotional traditions take it as Krishna as the personal God.