זוהר שמות — דף יד ע”ב

When Rabbi Shimon bar Yochai opens his mouth to teach Torah, sparks of fire fly in all directions and reach seventy myriads of celestial chariots. All worlds shake and all thrones and firmaments fall silent when the righteous one reveals the secrets of Torah. Six degrees descended with Jacob into Egypt, corresponding to the six degrees of Israel, and to the six steps of the upper and lower throne. Rabbi Elazar asked why Israel was exiled specifically to Egypt and not to another land, in order to understand the secret of the first exile.