Contradiction with Proverbs 12:22
This verse highlights the wickedness of lying lips, whereas in 1 Samuel 20:39, the boy is kept in ignorance as part of a secretive plan.
Proverbs 12:22: Lying lips [are] abomination to the LORD: but they that deal truly [are] his delight.
Contradiction with Exodus 20:16
The commandment here prohibits bearing false witness, contrasting with the secrecy found in 1 Samuel 20:39.
Exodus 20:16: Thou shalt not bear false witness against thy neighbour.
Contradiction with Colossians 3:9
Advises against lying to one another, while 1 Samuel 20:39 involves withholding the truth.
Colossians 3:9: Lie not one to another, seeing that ye have put off the old man with his deeds;