Verse 13. "And he changed his behaviour" - Some imagine David was so terrified at the danger to which he was now exposed, that he was thrown into a kind of frenzy, accompanied with epileptic fits. This opinion is countenanced by the Septuagint, who render the passage thus: idou idete andra epilhton; "Behold, ye see an epileptic man. Why have ye introduced him to me?" mh elattoumai epilhptwn egw; "Have I any need of epileptics, that ye have brought him to have his fits before me, (epilhpteuesqai prov me?") It is worthy of remark, that the spittle falling upon the beard, i.e., slavering or frothing at the mouth, is a genuine concomitant of an epileptic fit.
If this translation be allowed, it will set the conduct of David in a clearer point of view than the present translation does. But others think the whole was a feigned conduct, and that he acted the part of a lunatic or madman in order to get out of the hands of Achish and his courtiers. Many vindicate this conduct of David; but if mocking be catching, according to the proverb, he who feigns himself to be mad may, through the just judgment of God, become so. I dare not be the apologist of insincerity or lying.
Those who wish to look farther into this subject may consult Dr. Chandler, Mr. Saurin, and Ortlob, in the first volume of Dissertations, at the end of the Dutch edition of the Critici Sacri.
Verse 15. "Shall this fellow come into my house?" - I will not take into my service a man who is liable to so grievous a disease. Chandler, who vindicates David's feigning himself, mad, concludes thus: "To deceive the deceiver is in many instances meritorious, in none criminal. And what so likely to deceive as the very reverse of that character which they had so misconstrued? He was undone as a wise man, he had a chance to escape as a madman; he tried, and the experiment succeeded." I confess I can neither feel the force nor the morality of this. Deceit and hypocrisy can never be pleasing in the sight of God.