1 Samuel 21:11-15 New English Translation (NET Bible)
11 The servants of Achish said to him, “Isn’t this David, the king of the land? Isn’t he the one that they sing about when they dance, saying,
‘Saul struck down his thousands,
12 David thought about what they said[a] and was very afraid of King Achish of Gath. 13 He altered his behavior in their presence.[b] Since he was in their power,[c] he pretended to be insane, making marks on the doors of the gate and letting his saliva run down his beard.
14 Achish said to his servants, “Look at this madman! Why did you bring him to me? 15 Do I have a shortage of fools so that you have brought me this man to display his insanity in front of me? Should this man enter my house?”