Contradiction with Exodus 20:16
This verse instructs not to bear false witness, while in 1 Samuel 16:4, Samuel must conceal his true purpose from Saul.
Exodus 20:16: Thou shalt not bear false witness against thy neighbour.
Contradiction with Matthew 5:37
This verse encourages honesty and straightforwardness, which seems contrary to the indirect approach Samuel uses in 1 Samuel 16:4.
Matthew 5:37: But let your communication be, Yea, yea; Nay, nay: for whatsoever is more than these cometh of evil.
Contradiction with Proverbs 12:22
This verse states that lying lips are an abomination, yet in 1 Samuel 16:4, Samuel is essentially instructed to withhold the full truth to protect himself and anoint David secretly.
Proverbs 12:22: Lying lips [are] abomination to the LORD: but they that deal truly [are] his delight.