Purchasing a friend for spiritual growth:[1]
Having a good friend which one can share his spiritual growth and Torah learning with is very important, and in one aspect is even more important than having a Rav. This can be derived from the Mishneh[2] which states that “One is to make himself a Rav and buy himself a friend”, hence teaching us that one must even spend money in order to acquire a friend. In addition, one is required to spend energy in his quest in finding a friend. This is imperative for one’s spiritual growth and success in Torah learning.
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[1] Igros Kodesh 13/16
[2] Pirkeiy Avos 1