Genesis 3:2

And the woman said to the serpent, From the rest of the fruits of the trees of the garden we have power to eat;

עץ הגן נאכלת, “we can eat from the trees of the garden and do not need to endanger our lives by eating from the tree that G’d has prohibited us to eat from on pain of death.” Having said this, however, her power of imagination kept nagging at her weighing the possibility that G’d might indeed be jealous of competition from his creature. Her doubt, i.e. the voice of the evil urge, was expressed in the words

ותאמר, not so, said Chavah; G’d did not deny us the fruit of more than one single tree which is בתוך הגן שאמר לנו לא תאכלו מממנו ולא תגעו בו פן תמותון in the middle of the garden of which He has forbidden us to eat on pain of death. Perhaps it is in the nature of that tree that its fruit causes death to anyone eating from it. The meaning of the word פן in that verse is the same as אולי or שמא , “maybe.” G’d told Adam that he would certainly die if he ate from it, as the Torah wrote literally in 2,17 “on the day you will eat from it you will certainly die.” Seeing that she had not quoted the prohibition correctly as G’d had not said anything about maybe dying as a result of eating from the tree, we must assume that Chavah had invented this word meaning for it to apply to touching the tree, an addition which had been altogether her own. She meant to say that G’d so loves us that He denied us to touch the tree as a safeguard against eating from it.
An alternate way of explaining the words פן תמותון is similar to פן תשיב את בני שמה which Avraham warned Eliezer about (Genesis 24,6) which meant “do not bring back!” or Genesis 30,24) פן תדבר עם יעקב, “do not speak to Yaakov, etc.,” G’d warning Lavan.