The Gorakhbodh
The original source (now extinct): http://www.hubcom.com/tantric/gorakh.htm

Macchendra: Let the unattached (awadhu, avadhuta) live at the monastery (hat) or be on the road, resting in the shadow of the trees; he should renounce desire, cruelty, greed, delusion, and the illusion of Samsar (Kama, Krodha, Lobha, Moha and Samsar ki Maya); he should hold converse (gosht) with himself and contemplate the Endless (Ananta); he should sleep little and eat little. In the beginning the disciple should live thus. Thus speaks Macchendra. [2]
Gorakh: What should he see, what contemplate, and what treat as the essence (sar); with what should he shave his head and with the knowledge of what should he try to cross (the ocean of Samsar)?
Macchendra: He should see himself, contemplate the Endless (Ananta), and fix upon Reality as the essence; he should shave his head with (or after receiving) the word of the teacher (Guru ka Shabda), and should cross over with the aid of Divine knowledge (Brahma Gyana). [4]
Gorakh: What is the teaching (upadesh) of the Guru's order or doctrine (Ades)? Where does the void (Sunya) reside? Who is the Guru of the word (Shabda)?
Macchendra: The most wonderful (anupam) is the teaching of the Guru (Ades); the void (Sunya) resides within us and Realisation (parcha or parichaya) is the Guru of the word (shabda). [6]