One of two named trees in the Garden of Eden.
God commanded Adam not to eat fruit from this tree, and Eve knew the prohibition given to the humans. Yet, being tempted by the crafty serpent (Satan), Eve ate the fruit from the forbidden tree and gave some to Adam who was with her.
In succumbing to temptation and eating the fruit, Adam and Eve committed the first human sin. In their sin, as apparently affected by the fruit, they realized their nakedness and separation from God.