David replied, “Then you will come to know what your servant can do.” “Very well,” said Achish. “I will make you my bodyguard for life.”
Jewish Publication Society of America Version (JPS1917) - 1 Samuel 28:2 >And David said to Achish: 'Therefore thou shalt know what thy servant will do.' And Achish said to David: 'Therefore will I make thee keeper of my head for ever.'