Did David play a harp for Saul?

16:23 And it came to pass, when the evil spirit from God was upon Saul, that David took an harp, and played with his hand: so Saul was refreshed, and was well, and the evil spirit departed from him.

17:50 So David prevailed over the Philistine with a sling and with a stone, and smote the Philistine, and slew him; but there was no sWord in the hand of David.