Bhagavad Gita, Chapter 14, Verse 1

The Deity said: Again shall I tell you that supreme knowledge which is above all knowledge, having known which all the Munis have attained to high perfection after this life.

This teaching is named here as real and complete, the very knowledge that carried saints all the way to perfection.

Krishna doesn't introduce this as a minor addendum, he ties it directly to the highest possible outcome. Real weight is placed on what's about to be explained before a single word of it arrives.