NET
2 David replied to Achish, “That being the case, you will come to know what your servant can do!” Achish said to David, “Then I will make you my bodyguard from now on.”
Darby
2 And David said to Achish, Thereby thou shalt know what thy servant can do. And Achish said to David, Therefore will I make thee keeper of my person for ever.
KJV
2 And David said to Achish, Surely thou shalt know what thy servant can do. And Achish said to David, Therefore will I make thee keeper of mine head for ever.