This sample from the Breslov Pirkey Avot corresponds to the chapter to be studied this coming Shabbos, Acharey Mos-Kedoshim. (Unlike most postings on this website, transliterations from Hebrew in this book reflect the Sefardic pronunciation.)
רַבִּי חֲנִינָא בֶּן חֲכִינַאי אוֹמֵר, הַנֵּעוֹר בַּלַּיִלָה וְהַמְהַלֵּךְ בַּדֶּרֶךְ יְחִידִי וְהַמְפַנֶּה לִבּוֹ לְבַטָּלָה, הֲרֵי זֶה מִתְחַיֵּב בְּנַפְשׁוֹ:
Rabbi Chanina ben Chakhinai said, “He who stays awake at night, and who walks the road alone, and who turns his heart to naught – he is responsible for his soul.” (3:4)
Digest of Commentaries:
Rabbi Chanina ben Chakhinai was a prominent disciple of Rabbi Akiva, from whom he received instruction in both the revealed and concealed aspects of the Torah.
He who stays awake at night, and who walks the road alone, and who turns his heart to naught—he is responsible for his soul. According to one view, each of these three behaviors endangers a person either physically or spiritually. According to another view, the night is a time of danger, and traveling alone is also dangerous. But if a person in either situation were to occupy his thoughts with Torah, the Torah would protect him from harm (Bartenura).
He who stays awake at night, and who walks the road alone, and who turns his heart to naught – he is responsible for his soul
Rebbe Nachman: The words of this teaching allude to the power of hitbodedut.
“He who stays awake at night” refers to the person who stays awake at night, secluding himself with God and expressing his thoughts and feelings to his Creator. “And who walks the road alone” means he selects an isolated path in a place that people do not frequent. These are the ideal preconditions for hitbodedut and are conducive to attaining bitul ("nullification of the ego"). “And who turns his heart to naught (leVaTaLah)” means he empties his heart of all mundane concerns for the sake of BiTuL, letting his soul be subsumed within Godliness. “He is responsible (mitChaYeV) for his soul.” Indeed, the entire world, together with his soul, is absorbed into its source in God, Who is the Necessary Existent (MeChuYaV HaMetziyut).
Through hitbodedut, a person attains nullification of the ego, at which point his soul becomes reunited with God, along with the entire world which was created as the necessary arena for his free will (based on Likutey Moharan I, 52).
Reb Noson: The most basic method for coping with all forms of suffering—whether those experienced by the Jewish people collectively or by each Jew individually—is self-nullification. One should close his eyes and completely nullify all sensory awareness until his very sense of self dissolves into the Infinite Light of God.
Anyone can do this, as I heard from the Rebbe’s holy mouth. Even though one may not be able to attain nullification of the ego to perfection like the great tzaddikim, nevertheless, anyone can do so for a limited time if he is truly determined (Likutey Halakhot, Netilat Yadayim Shacharit 4:4).
Devotion of the Ovdim
Many of the Breslover Chassidim who lived in Uman in the twentieth century were meticulous about practicing hitbodedut in the fields and forests at night in fulfillment of the Rebbe’s advice.
Led by Reb Elyakim Getzel, a descendent of Rebbe Nachman, a group of ovdim (“devotees”) would gather at midnight (chatzot) and go down to the river to immerse, breaking the ice to use the river as a mikvah. Their greatest worry was finding the hole in the broken ice again in order to re-emerge from the water. They would take along bundles of straw and make fires on the riverbank so they would not freeze when wet. Afterward they would spend many hours in hitbodedut in the forest before returning to town in time for the morning prayers.
One icy night, when the temperature dropped even below the sub-zero Ukrainian temperatures, nearly everyone in the group was unwilling to go out to the forest. Only Reb Elyakim Getzel and Reb Hirsch Leib Lippel ventured forth. With gusting winds piling the snow several feet high, Reb Hirsch Leib eventually could no longer keep pace and retreated. Reb Elyakim was the only one to forge ahead, performing his devotions alone in the forest (heard from Reb Hirsch Leib Lippel).
As a young Chassid, Reb Naftali Zvi Dubinsky (d. 1993) became a close follower of Reb Yaakov of Zhitomir (d. 1938), one of the Breslover ovdim, who explained to him the practice of going into the forest at night for hitbodedut and crying out to God in order to draw close to Him.
The first night that Reb Naftali went into the forest with his mentor, he heard screams that frightened him so much that he feared Reb Yaakov had been attacked by murderers. Running swiftly toward his teacher, he soon saw that Reb Yaakov was safe. “What danger made you scream so terribly?” Reb Naftali asked.
Reb Yaakov replied, “That’s the way you, too, would scream if you really felt the danger of the evil inclination, and how it keeps trying to snuff out the spiritual life of a person!” (heard from Reb Naftali Zvi Dubinski).