Génesis 3:3 Midrash: Otzar Midrashim, Pirkei DeRabbi Eliezer, Midrash Aggadah & Bereshit Rabbah

And the tree of knowledge of good and evil – Rabbi Pinchas ben Yair said: Until Adam the first man ate from it, this tree was not called by [any] name, but rather just tree, like all the other trees. But from when he ate and transgressed the decree of the Holy One, blessed be He, its name was called, the tree of knowledge of good and evil, based on [what happened to] it later. This is like we find with many things, the names of which are written earlier based on [what happened to] it later, like and they struck the whole territory of the Amalekite (Genesis 14:7). But why was its name called, good and evil? Since the Holy One, blessed be He, informed him not to eat from it, neither the good nor the evil. This is like He said to Lavan: Guard yourself not to speak to Jacob either good or evil (Genesis 31:29); we cannot say anything to you, evil or good (Genesis 24:50); He shall not search whether it be good or bad (Leviticus 27:33). And from here (another textual variant: And from where [do]) we say that before he ate from the tree, he knew good and evil. Indeed, we find that he gave names to all of the creatures from his great wisdom that [God] gave to him, as it is stated: And Adam gave them names (Genesis 2:20). And we also found that the Holy One, blessed be He, created him in a goodly measure, in His image and in His likeness, so He did not create [him as] a lacking creature. And we also found that is written about him that he was full of wisdom and understanding, as it is stated, full of wisdom and flawless in beauty. You were in Eden, the garden of God (Ezekiel 28:12-13). And from where do you say that the tree was not called the tree of knowledge from the beginning? From the woman’s answer to the snake. See what she answered him: But of the fruit of the tree which is in the midst of the garden, God has said, “You shall not eat of it” (Genesis 3:3). And she did not say, “Of the fruit of the tree of knowledge of good and evil.” And also at the time when the Holy One, blessed be He, asked Adam, “Why are you hiding,” He said to him, Did you eat of the tree from which I had commanded, etc. (Genesis 3:11); and He did not say, “of the tree of knowledge of good and evil.” And for another thing as well was its name called, the tree of knowledge of good and evil [bad] – because through it, man knew many bad things. As until man transgressed the command, toil, effort, cold, heat, and pain had not been decreed upon him, nor anything that would hurt him. But once he transgressed the Omnipresent’s decreed statute, all of these bad things affected him… And why did the Holy One, blessed be He, command him that he should eat from all of the trees of the garden, but prevented him from one of them? So that he should constantly see it, remember his Creator, and recognize that the yoke of his Maker is upon him and that he should not become haughty.

The serpent argued with itself, saying: If I go and speak to Adam, I know that he will not listen to me, for a man is always hard (to be persuaded), as it is said, "For a man is churlish and evil in his doings" (1 Sam. 25:3); but behold I will speak to Eve, for I know that she will listen to me; for women listen to all creatures, as it is said, "She is simple and knoweth nothing" (Prov. 9:18). The serpent went and spake to the woman: || Is it (true that) you also have been commanded concerning the fruit of the tree? She said (to him): Yes, as it is said, "Of the fruit of the tree which is in the midst of the garden" (Gen. 3:8). And when the serpent heard the words of Eve, he found a way through which he could enter (to approach her), so he said to her: This precept is nought else except the evil eye, for in the hour when ye eat thereof, ye will be like Him, a God. Just as He creates worlds and destroys worlds, so will ye be able to create worlds and to destroy worlds. Just as He slays and brings to life, so also will ye be able to kill and to bring to life, as it is said, "For God doth know that in the day ye eat thereof, then your eyes shall be opened" (Gen. 3:5).

And from the tree of knowledge of good and bad. The Holy One did not say, the tree of knowledge, rather it was Moses who wrote down the Torah and called it the tree of knowledge. And also, Adam did not know that it was the tree of knowledge, which is why the woman said to the snake, and from the fruit of the tree that is within the garden (Genesis 3:3) and she did not say, and from the fruit of the tree of knowledge.