The Egyptian here used a common term for referring to God or the gods. He wanted David to swear to the God that David believed in before he took him to the camp. Apart from David’s word, he had no guarantee that David would not simply hand him over to his old master in exchange for some kind of reward. David must have agreed to take an oath since the man proceeded to lead them to the Amalekite camp.1
15 David lui dit: Veux-tu me faire descendre vers cette troupe? Et il répondit: Jure-moi par le nom de Dieu que tu ne me tueras pas et que tu ne me livreras pas à mon maître, et je te ferai descendre vers cette troupe.