"You will not certainly die," the serpent said to the woman. — TNIV, Gen.3:4.
Genesis 3: 2-5
At this the woman said to the serpent: “Of the fruit of the trees of the garden we may eat. But as for [eating] of the fruit of the tree that is in the middle of the garden, God has said, ‘Y OU must not eat from it, no, YOU must not touch it that YOU do not die.’” At this the serpent said to the woman: “Y OU positively will not die. For God knows that in the very day of YOUR eating from it YOUR eyes are bound to be opened and YOU are bound to be like God, KNOWING good and bad.”
Genesis 3: 22-24
And Jehovah God went on to say: “Here the man has become like one of us in knowing good and bad, and now in order that he may not put his hand out and actually take [fruit] also from the tree of life and eat and live to time indefinite,—” With that Jehovah God put him out of the garden of E´den to cultivate the ground from which he had been taken. And so he drove the man out and posted at the east of the garden of E´den the cherubs and the flaming blade of a sword that was turning itself continually to guard the way to the tree of life.
The serpent said they would not die and that they would come to know good and bad. God admitted that they did come to know good and bad and he only drove them out of the garden. They continued to live. God lied and the serpent told the truth.