When David came to Saul and entered his service, Saul admired him greatly, and David became his armor-bearer.

Then Saul sent word to Jesse: “Let David remain in my service, for I am pleased with him.”

Then Saul said, “Listen, son of Ahitub!”

“I’m at your service, my lord,” he said.

Now, Eli, was very old, - but he used to hear all that his sons did unto all Israel, and how they even lay with the women who did service, at the opening of the tent of meeting.

There was intense fighting against the Philistines during Saul's entire reign, and whenever Saul discovered a strong or valiant warrior, he would enlist him for service.