Zohar 3:175b

Jewish Mysticism
R. Hiyya began to expound, “the glory of God is to conceal the matter, the glory of kings is to search out the matter” (Prov. 25-2). “The glory of God is to conceal the matter,” for a person does not have permission to reveal secret matters for they have not been given permission to reveal matters that the Ancient of Days concealed, as it is said, “that they may eat their fill and cover that which the Ancient One [concealed]” (Isa. 23-18). “To eat their fill,” up to that place wherein they have permission [to reveal] and no more. Thus it is said, ve limekhaseh atik, verily (vada’y) that which the Ancient One (atik) covers.

Translated by Elliot Wolfson in- “Beautiful Maiden Without Eyes- Peshat and Sod in Zoharic Hermeneutics.” In The Midrashic imagination – Jewish exegesis, thought, and history. Edited by Michael Fishbane, Albany – State University of New York Press, 1993, pp. 155-203.