It was given to me by a Greek Drupla (soon to be Lama) friend of mine who probably got it during one of her two three year retreats at Dhagpo Kundreul Ling in France (thus explaining why the text is in French). I will ask her about the source the next time I talk to her.
Oh, by the way dzoki, since a tsog is a Vajrayana/tantric practice you will probably (definitely?) need a lung to do the specific practice.
With the eye of wisdom we discover a lot of anger in us, any amount of jealousy, resentment, ignorance, desire - mountains of emotion whose existence we would never have suspected in ourselves... We recognize that most of the faults we perceive in others are only the mirror of our own negativity, the reflection of our own disturbed feelings... At the same time, we relieve the world around us of the burden of our own negative judgements."
Gendun Rinpoche Heart Advice from a Mahamudra Master