Chandogya Upanishad
Prapathaka II, Khanda 12
The hiṅkâra is, he rubs (the fire-stick); the prastâva, smoke rises; the udgîtha, it burns; the pratihâra, there are glowing coals; the nidhana, it goes down; the nidhana, it is gone out. This is the Rathantara Sâman as interwoven in fire .