Contradiction with Exodus 12:40
This verse states that the children of Israel lived in Egypt for 430 years, which contradicts the implication of long-term habitation in the land of the Philistines in Genesis 21:34.
Exodus 12:40: Now the sojourning of the children of Israel, who dwelt in Egypt, [was] four hundred and thirty years.
Contradiction with Acts 7:6
This verse mentions that Abraham's descendants would be in a foreign land and enslaved for 400 years, conflicting with the peaceful dwelling in the land of the Philistines implied in Genesis 21:34.
Acts 7:6: And God spake on this wise, That his seed should sojourn in a strange land; and that they should bring them into bondage, and entreat [them] evil four hundred years.