Genesis 2:17

"'but you must not eat from the tree of the knowledge of good and evil, for when you eat of it you will surely die.'"  Genesis 2:17

Here's the "but" statement following the last verse.  In the Qbible it notes that "surely die" is a casual statement and "die" can be either "die" or "kill."  Maybe the end of that verse should be read more like "the day you eat of it, it will cause your death."

This article states the proper translation should be "dying you shall die."  It argues that eating from this tree would cause them to begin dying immediately.  When you think about our one bodies that the older we get the more and more they wear out, this does make some sense.  Eating from this tree started the dying process.  It may have taken years or centuries, but in the end both Adam and Eve died.

This verse may also be pointing out that killing would enter the earth.  Nowhere before this point does God give any creature anything but plants to eat.  One eventual outcome from eating of this tree would be not only the killing of other humans, but also animals killing other animals.  It's amazing the impact of one sin had on all creation.  How much of an impact do our individual sins today have?