Are you talking about the "Joy Joy Joy" song? Below paraphrased from: http://en.wikipedia.org/wiki/I've_Got_the_Joy_Joy_Joy_Joy_(song)

I've got the joy, joy, joy, joy
Down in my heart (Where?)
Down in my heart (Where?)
Down in my heart
I've got the joy, joy, joy, joy
Down in my heart (Where?)
Down in my heart to stay

Subsequent lyrics include:
I've got the peace that passes understanding...
Down in my heart (Where?)
Down in my heart (Where?)
Down in my heart
I've got the peace that passes understanding...
Down in my heart (Where?)
Down in my heart to stay

There is also a song that is titled "Peace That Passes All Understanding " that is sung by Richie Furay.

Lyrics here: http://www.smartlyrics.com/Song617997-Richie-Furay_Peace-ThatPasses-All-Understanding-lyrics.aspx

Wrong answers on both answers - thanks for reply though