Bhagavad Gita, Chapter 18, Verse 62

Take refuge in Him with all your heart, O Bhârata; by His grace shall you attain supreme peace and the eternal abode.

Real, whole surrender is asked for here, not a partial or occasional gesture.

Krishna names the full extent of what's being asked, one's entire being, not just certain actions or moments. Real peace is tied directly to real completeness in that surrender.