In Sichah 9 of Sichos HaRan, Rebbe Nachman brings a statement from the Baal Shem Tov that a person should not give a knife as a gift. He did not explain this statement. He mentioned it without any elaboration.
Rabbi Tzvi Aryeh Rosenfeld gave an explanation for this prohibition of giving knives as a gift. A knife is the symbol of Esav, who lives by the sword. This is a very low level. On the other hand, giving a gift to a tzaddik, the Gemara says, is like bringing bikkurim, like bringing a korban. Even if the person receiving the gift isn’t a tzaddik, we see that giving a gift is on a tremendously high level. It would not be appropriate to do this with the tools of Esav harasha. Therefore, we do not give knives as a gift.
This is one explanation for the Baal Shem Tov’s statement, but there is something else very important that we can learn from this Sichah. The Rebbe brought this unusual statement without giving any explanation. From here we can learn a lesson in emunas chakhamim, believing in tzaddikim. If a tzaddik gives a directive, even if we don’t understand it, we are obligated to follow. It is permitted to ask questions and to delve into why it is so with the caveat that we first fully accept upon us to follow even if in the end we do not understand. This is what we agreed to when we received the Torah and said “na’aseh venishmah”, first we accept upon ourselves to do it, and then we will learn about it. One of the mitzvos of the Torah is to follow the chakhamim of the generation, and therefore we are obligated to obey their decrees to the same extent as those written in the Torah, even if do not understand them.
Believing in the tzaddikim is part and parcel of the mitzvah of believing in HaShem. When HaShem came down to Har Sinai to give the Torah, he told Moshe that he would let Bnei Yisrael hear Him talking to Moshe so that “also in you they will believe forever”. The first of the Ten Commandments we heard at Har Sinai is to believe in HaShem, but the method in which it was given over was so that we would believe in Moshe Rabbeinu.
Rebbe Nachman explains many times that the tzaddik of each generation is an aspect of Moshe Rabbeinu. We cannot receive the Torah, and our serving HaShem is not complete, without believing in the tzaddik. We should all be zocheh to seek out and find the true tzaddik, to believe in him and follow his advice, and through that to come closer to HaShem.