Zohar 2:60a-b

Jewish Mysticism
What is [the meaning of what is] written, “So he [Moses cried out to the Lord, and the Lord showed him a piece of wood (etz)” (Exod. 15-25)? The word etz is nothing but the Torah [b. Arakhin 15b], as it is written, “She is a tree of life (etz hayyim) to those who grasp her” (Prov. 3-18). And the [word] Torah is nothing but the Holy One, blessed be He. R. Abba said- the [word] tree is nothing but the Holy One, blessed be He, as it is written, “For man [is] the tree of the field” (Num. 20-19, the tree of the field (etz ha sadeh) indeed (vada’y), i.e., the tree of the field of holy apples.

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.