| Clarke's Commentary on the Bible 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.
Gill's Exposition of the Entire BibleHave I need of madmen?.... Or fools, do I want them? have not I enough of them already at my court? I want wise men, and not fools and madmen. The Jews say (w) that the wife and daughter of Achish were mad; that while David was playing the fool and madman without, they were acting the same part within; so that Achish had enough of that sort of diversion, if it was to be reckoned such; as it was according to the taste of some persons, who used, as in later so in earlier times, to keep fools in their houses to make them sport; but Achish had enough of that, and too much, at least needed no more: that ye have brought this fellow to play the madman in my presence? or act the part of a fool before me: shall this fellow come into mine house? court or palace, and have a post there; you need be in no pain about it; he is neither agreeable to me, nor fit for any; and therefore Achish drove him away as a fool or madman, instead of imprisoning him as an enemy, or taking away his life; see the title of the thirty fourth psalm, Psalm 34:1. (w) Midrash Tillim apud Abarbinel. in loc.
Geneva Study BibleHave I need of mad men, that ye have brought this fellow to play the mad man in my presence? {k} shall this fellow come into my house? (k) Is he fit to be in a king's house.
Wesley's Notes 21:15 Mad men - It is highly probable, Achish was aware, that this madness was counterfeit. But being desirous to preserve David, he speaks as if he thought it real.
Matthew Henry's Concise Commentary21:10-15 God's persecuted people have often found better usage from Philistines than from Israelites. David had reason to put confidence in Achish, yet he began to be afraid. His conduct was degrading, and discovered wavering in his faith and courage. The more simply we depend on God, and obey him, the more comfortably and surely we shall walk through this troublesome world. | 
