2 Samuel 15:34

Then mayest thou for me defeat the counsel of Ahithophel. David was thus meeting treachery by treachery, and we cannot approve of it, even granting that Ahithophel's conduct was base and selfish, while Hushai was risking his life for his master. Still, he was sent back to tell a falsehood, and his excuse was necessity; for Ahithophel was so sagacious that, if his counsel were not upset, David's cause was lost. It was not Christian morality, but yet it has a sort of nobleness about it in Hushai's devotion to his king. And even now, in war and diplomacy, such acts are not uncommon, and a distinction is unhappily drawn between political and social morality. Even in common life immoral doings are often sanctioned by use. Thus many customs of trade are frauds, considered legitimate because generally practised. Even among ourselves Christian morality is far below the level of our Master's teaching; and the Old Testament must not be taken as approving all that it records. Similar blame does not attach to Zadok and Abiathar. They were known to be David's friends, and had even tried to go with him, bearing with them the ark. They professed no friendship for Absalom, and returned for no covert purpose, looking for protection, not to guile, but to their sacred office. And Absalom would be glad to have them in his power, and would make them continue the customary sacrifices, and, if his rebellion proved successful, would force them to anoint him, and so give his usurpation a religious sanction. But he would tell them none of his plans, nor would they try to insinuate themselves into his confidence. They would have a perfect right to be useful in any way they could to their true master, but would do so at the risk of severe punishment. Hushai's way of defeating Ahithophel was treacherous; but there was no deceit in the young men carrying a message from him, for they were openly David's friends.