Then there was a famine in the days of David three years, year after year; and David inquired of the LORD. And the LORD answered, It is for Saul, and for his bloody house, because he slew the Gibeonites. Then there was a famine - Of this famine we know nothing; it is not mentioned in any part of the history of David.
Because he slew the Gibeonites - No such fact is mentioned in the life and transactions of Saul; nor is there any reference to it in any other part of Scripture.