1 Samuel 28:1-2

New International Version - UK

28 In those days the Philistines gathered their forces to fight against Israel. Achish said to David, ‘You must understand that you and your men will accompany me in the army.’

² David said, ‘Then you will see for yourself what your servant can do.’

Achish replied, ‘Very well, I will make you my bodyguard for life.’