Vijnana Bhairava Tantra · Dharana 2 · Verse 25
Where the breath turns
Take in not only the exact turning point of the breath, but a little of the breath on either side of it. Rest attention at the place where the breath changes direction, rather than in the thoughts that run before and after it.
Older line
Whether the breath is within or without, do not turn back from the two spaces where it pauses. So, O Bhairavi, through the Goddess the very form of Bhairava is revealed.