The Tosher Rebbe related how once after the the holy Ba’al Shem Tov had already passed away, he had revealed himself in a vision to his son, Rav Tzvi, . Rav Tzvi asked his departed father, the Ba’al Shem, “Please teach me how to serve Hashem properly.”
The holy Ba’al Shem Tov depicted for his son a tall mountain with a steep cliff; at the edge of the cliff, peering down, one could see a raging, roaring, deep body of water. “My son,” said the Ba’al Shem, “you should imagine that you are always standing at the top of this mountain at the edge of the cliff and then cast yourself from the mountain and plunge yourself deep into the river’s waters down below! That is how you must serve Hashem, always be prepared to be moser nefesh – be ready to give yourself and to sacrifice for Hashem in order to sanctify His Name!” (Avodas Avoda Sichos Kodesh I p. 87)
