Contradiction with 1 Samuel 20:30
Explains that Saul was enraged by Jonathan's loyalty to David, while 1 Samuel 20:7 suggests Saul might respond favorably if David was found to be absent.
1 Samuel 20:30: Then Saul's anger was kindled against Jonathan, and he said unto him, Thou son of the perverse rebellious [woman], do not I know that thou hast chosen the son of Jesse to thine own confusion, and unto the confusion of thy mother's nakedness? [Thou...: or, Thou perverse rebel: Heb. Son of perverse rebellion]
Contradiction with 1 Samuel 19:6
Saul swore to Jonathan not to kill David, whereas 1 Samuel 20:7 implies David is in danger.
1 Samuel 19:6: And Saul hearkened unto the voice of Jonathan: and Saul sware, [As] the LORD liveth, he shall not be slain.
Contradiction with Matthew 5:44
Advises to love your enemies, whereas 1 Samuel 20:7 involves preparing for a threat.
Matthew 5:44: But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you;
Contradiction with Proverbs 27:6
Discusses the value of a friend's wounds over an enemy's kisses, contrasting with Jonathan's act to protect David by gauging Saul's intentions in 1 Samuel 20:7.
Proverbs 27:6: Faithful [are] the wounds of a friend; but the kisses of an enemy [are] deceitful. [deceitful: or, earnest, or, frequent]
Contradiction with Psalm 55:21
Describes deceitful speech, in contrast to Jonathan's honesty with David in 1 Samuel 20:7.
Psalm 55:21: [The words] of his mouth were smoother than butter, but war [was] in his heart: his words were softer than oil, yet [were] they drawn swords.