Kabbalah su Levitico 25:55

[The master of Kabbalah] also possesses a third advantage which is entwined in the two preceding ones. That is, one who serves [God] according to the plain meaning [of the Torah] and is drawn after it alone is classified according to the esoteric significance of the term “servants,” as it is written, For it is to Me that the children of Israel are servants; they are My servants (Lev. 25:55). He who occupies himself with Kabbalah and serves [God] according to the way of Kabbalah in the recondite meaning of the “intention” of the commandments is called “son.” Thus [Scripture] states, You are sons to the Lord your God (Deut. 14:1). There are many similar [verses], such as My firstborn son is Israel (Exod. 4:22). These praises are elaborated upon in the Tikkunim, the Ra’aya Mehemna, and countless times in the pikkudin.