This Bible contradiction is from the Skeptic's Annotated Bible.
Psalm 90:10 View context
The days of our years [are] threescore years and ten; and if by reason of strength [they be] fourscore years, yet [is] their strength labour and sorrow; for it is soon cut off, and we fly away.
Genesis 6:3 View context
And the LORD said, My spirit shall not always strive with man, for that he also [is] flesh: yet his days shall be an hundred and twenty years.