ב"ה, ט"ז אד"ר, תשכ"ז
ברוקלין.
שלום וברכה!
...לכתבו אודות לימוד בס' קבלה - לאחרי שתהי' לו הבנה טובה בס' חסידות שלמד, ילמוד באותם ס' קבלה שהובאו במאמרי חסידות (שמזה הוכחה שמאושרים הם - וכידוע הכרח הזהירות שצ"ל בזה).
B"H, 16 Adar II, 5727, Brooklyn.
Shalom u'Vrachah!
...Regarding your writing about studying Kabbalah texts—after you have a good understanding of the Chassidus texts you have learned, you should study those Kabbalah works that are cited in the discourses of Chassidus (from which it is evident that they are approved—as is well known, caution is absolutely necessary in this matter).
Summary
The Rebbe teaches that one should approach the study of Kabbalah only after gaining a strong foundation in Chassidus and should limit oneself to those Kabbalah works referenced in Chassidus, emphasizing the importance of caution in these studies.