1 Samuel 14:8-20 (NIV):
[8] Jonathan said, “Come on, then; we will cross over toward them and let them see us. [9] If they say to us, ‘Wait there until we come to you,’ we will stay where we are and not go up to them. [10] But if they say, ‘Come up to us,’ we will climb up, because that will be our sign that the Lord has given them into our hands.”

[11] So both of them showed themselves to the Philistine outpost. “Look!” said the Philistines. “The Hebrews are crawling out of the holes they were hiding in.” [12] The men of the outpost shouted to Jonathan and his armor-bearer, “Come up to us and we’ll teach you a lesson.”

So Jonathan said to his armor-bearer, “Climb up after me; the Lord has given them into the hand of Israel.”

[13] Jonathan climbed up, using his hands and feet, with his armor-bearer right behind him. The Philistines fell before Jonathan, and his armor-bearer followed and killed behind him. [14] In that first attack Jonathan and his armor-bearer killed some twenty men in an area of about half an acre.

[15] Then panic struck the whole army—those in the camp and field, and those in the outposts and raiding parties—and the ground shook. It was a panic sent by God.

[16] Saul’s lookouts at Gibeah in Benjamin saw the army melting away in all directions. [17] Then Saul said to the men who were with him, “Muster the forces and see who has left us.” When they did, it was Jonathan and his armor-bearer who were not there.

[18] Saul said to Ahijah, “Bring the ark of God.” (At that time it was with the Israelites.) [19] While Saul was talking to the priest, the tumult in the Philistine camp increased more and more. So Saul said to the priest, “Withdraw your hand.”

[20] Then Saul and all his men assembled and went to the battle. They found the Philistines in total confusion, striking each other with their swords.