David pretends to be a crazy man before Achish, king of Gath (1 Samuel 21:10-15). The text reads, “And David rose and fled that day from Saul and went to Achish the king of Gath. And the servants of Achish said to him, “Is not this David the king of the land? Did they not sing to one another of him in dances,
‘Saul has struck down his thousands,
and David his ten thousands’?”
And David took these words to heart and was much afraid of Achish the king of Gath. So he changed his behavior before them and pretended to be insane in their hands and made marks on the doors of the gate and let his spittle run down his beard. Then Achish said to his servants, “Behold, you see the man is mad. Why then have you brought him to me? Do I lack madmen, that you have brought this fellow to behave as a madman in my presence? Shall this fellow come into my house?”
The purpose was a matter of life or death but it was driven by his own self-interest. David was trying to protect himself from being killed while being pursued by Saul.
Another example of David in 1 Samuel is found in chapter twenty-seven. Here, David deceives Achish concerning where he had raided (1 Samuel 27:8-12). It reads, “Now David and his men went up and made raids against the Geshurites, the Girzites, and the Amalekites, for these were the inhabitants of the land from of old, as far as Shur, to the land of Egypt. And David would strike the land and would leave neither man nor woman alive, but would take away the sheep, the oxen, the donkeys, the camels, and the garments, and come back to Achish. When Achish asked, “Where have you made a raid today?” David would say, “Against the Negeb of Judah,” or, “Against the Negeb of the Jerahmeelites,” or, “Against the Negeb of the Kenites.” And David would leave neither man nor woman alive to bring news to Gath, thinking, “lest they should tell about us and say, ‘So David has done.’” Such was his custom all the while he lived in the country of the Philistines. And Achish trusted David, thinking, “He has made himself an utter stench to his people Israel; therefore he shall always be my servant.” Achish was an enemy but David positioned himself as a trustworthy soldier but used lies to accomplish it.