Contradiction with Leviticus 19:31
This verse warns against turning to mediums and seeking out spirits, contradicting the actions taken in 1 Samuel 28 with the medium at Endor.
Leviticus 19:31: Regard not them that have familiar spirits, neither seek after wizards, to be defiled by them: I [am] the LORD your God.
Contradiction with Deuteronomy 18:10-12
These verses strictly prohibit consulting with familiar spirits, which is what Saul does in 1 Samuel 28.
Deuteronomy 18:10-12: There shall not be found among you [any one] that maketh his son or his daughter to pass through the fire, [or] that useth divination, [or] an observer of times, or an enchanter, or a witch,
Contradiction with 1 Chronicles 10:13-14
These verses highlight the consequences of Saul consulting a medium, contrasting with the narrative where it seems like just another event.
1 Chronicles 10:13-14: So Saul died for his transgression which he committed against the LORD, [even] against the word of the LORD, which he kept not, and also for asking [counsel] of [one that had] a familiar spirit, to enquire [of it]; [committed: Heb. transgressed]
Contradiction with Isaiah 8:19
This verse advises to seek God rather than consulting spirits, contradicting Saul's choice in 1 Samuel 28.
Isaiah 8:19: And when they shall say unto you, Seek unto them that have familiar spirits, and unto wizards that peep, and that mutter: should not a people seek unto their God? for the living to the dead?