Musar su Esodo 13:18

Just as the six days of creation being "G–d's days," are viewed as the equivalent of one thousand years each, so the Kabbalists view this as a reference to the six thousand years this physical world will exist before a period of one thousand years of ruin, i.e. a period without creative activity, ישבות. This process is supposed to repeat itself seven times until the year fifty thousand, which is the סוד, secret of the יובל, ultimate freedom. The Exodus is to be viewed as a branch of the tree which represents universal history. This idea was hinted at already at the time of the Exodus, when Israel escaped the power (limitations imposed on all creatures) of the fifty levels of בינה, insight. This is the deeper meaning of וחמושים עלו בני ישראל in Exodus 13,18, i.e. that the target of the ascent was "fifty." The idea is that when attaining the fiftieth level, one has achieved more than merely escaping a branch of the fifty levels of בינה. [These 50 gates of בינה are perhaps identical with the 50 gates of טומאה that we are all familiar with from Midrashic literature. At any rate, they represent different levels of restraint, exposure to the pull of the material universe. Ed.] The fact that יציאת מצרים is mentioned in the Torah exactly fifty times may further reinforce the idea that after reaching level fifty freedom becomes absolute. The author suggests that the average lifespan of man of seventy years is a further reminder of this concept, allowing for the fact that man is not judged by Heaven for misdemeanours committed during the first twenty years of his life. Even the male Jewish servant who has his ear pierced, must go free not later than in the fiftieth year, יובל, which is the meaning of Exodus 21,6, "he shall serve לעולם."