Guhyasamaja

reference: "They practiced yogic exercises all night, performing them three times. First they practiced only the bebchung; then, the bebchen; and finally only dorbeb. As day broke, Chokling, who had a scarf Karmapa had given him when he visited Kham, wet it and put it around his back. 65 practitioners were able to perform the yogic exercises well. They all encircled the camp and everyone could see Chokling's body glowing as if on fire and with a lot of vapor rising".

Ref. material: The Life of Chokgyur Lingpa as told by Orgyen Tobgyal Rinpoche translated by Tulku Jigmey Khyentse and Erik Pema Kunsang

Rangjung Yeshe Publications.The Life of Chokgyur Lingpa.