This Bible contradiction is from the Skeptic's Annotated Bible.
Genesis 15:13 View context
And he said unto Abram, Know of a surety that thy seed shall be a stranger in a land [that is] not their's, and shall serve them; and they shall afflict them four hundred years;
Exodus 12:40 View context
Now the sojourning of the children of Israel, who dwelt in Egypt, [was] four hundred and thirty years.
Galatians 3:17 View context
And this I say, [that] the covenant, that was confirmed before of God in Christ, the law, which was four hundred and thirty years after, cannot disannul, that it should make the promise of none effect.