1 Samuel 21:10-15 NIV
That day David fled from Saul and went to Achish king of Gath. But the servants of Achish said to him, “Isn’t this David, the king of the land? Isn’t he the one they sing about in their dances:
“ ‘Saul has slain his thousands,
and David his tens of thousands’?”
David took these words to heart and was very much afraid of Achish king of Gath. So he pretended to be insane in their presence; and while he was in their hands he acted like a madman, making marks on the doors of the gate and letting saliva run down his beard.
Achish said to his servants, “Look at the man! He is insane! Why bring him to me? Am I so short of madmen that you have to bring this fellow here to carry on like this in front of me? Must this man come into my house?”
NIV: New International Version