1 Samuel 21:10

7 Now a certain man of the servants of Saul [was] there that day, detained before the LORD; and his name [was] Doeg, an Edomite, the chief of the herdmen that [belonged] to Saul.

8 And David said to Ahimelech, And is there not here under thy hand a spear or sword? for I have neither brought my sword nor my weapons with me, because the king's business required haste.

9 And the priest said, The sword of Goliath the Philistine, whom thou slewest in the valley of Elah, behold, it [is here] wrapped in a cloth behind the ephod: if thou wilt take that, take [it]: for [there is] no other save that here. And David said, [There is] none like that; give it to me.

10 And David arose, and fled that day for fear of Saul, and went to Achish the king of Gath.

11 And the servants of Achish said to him, [Is] not this David the king of the land? did they not sing one to another of him in dances, saying, Saul hath slain his thousands, and David his ten thousands?

12 And David laid up these words in his heart, and was greatly afraid of Achish the king of Gath.

13 And he changed his behavior before them, and feigned himself mad in their hands, and scrabbled on the doors of the gate, and let his spittle fall down upon his beard.