The Neschizer rebbe was told that a certain person was learning forbidden literature.
The Neschizer rebbe said to that man, “Tell me the truth about what I have heard about you.”
The man answered, “Heaven forbid, I am only learning books on grammar--dikduk.”
The Neschizer answered him, “That is connected to the idea of the ‘sufferings of poverty’--dikdukei aniyut.”
The man also said, “I sometimes study the Kuzari.”
The Neschizer said, “It is fitting to learn Talmud with the comments of the Rosh. Also learn the Duties of the Heart, but skip the Gate of Unity.”
And the Neschizer said, “It is clear to me that when I learned a page of Gemera my eyes would be illumined by that.” And he directed the man to recite Zohar on Sabbath morning before prayers.
Also when the completion of a tractate was made in his presence on the Three Weeks, to make it possible to eat meat, he would at times ask the man who had completed the tractate, “Do you learn Talmud with the Rosh?” People were not sure if he meant the work Ashri by the authority called the Rosh, or if he meant, “Did you learn using your head (‘rosh’)?”
The Neschizer also very much recommended learning the Shnei Luchos Habris.
He told a story that the author of the Shnei Luchos Habris had a student in his yeshiva who had difficulty paying attention.
One time the Shlah struck him and tore his ear. The student ran away and joined a band of thieves and became their leader, and he lived in the forest.
Hashem brought it about that the Shlah was so immersed in his thoughts of Torah learning that he lost his way in the forest and he came to that very forest, to that very house.
The student recognized him, but the Shlah did not recognize the student. And he stayed there on the holy Sabbath. After the holy Sabbath was over, the student told him, “Know that I am your student, So and So.” And in proof he showed him his torn ear. And he said, “If you can show me a way to repent, fine. But if not, I will kill you.”
The Shlah gave him a regimen of repentance: to place a small snake in a bottle and hang it around his neck and feed it every day for seven years from everything that he himself eats and drinks. Afterwards, the snake will arise and kill him, and that will be his atonement.
And with this regimen of repentance, the student became a perfect tzaddik.