It happened on the next day, that an evil spirit from God came mightily on Saul, and he prophesied in the midst of the house: and David played with his hand, as he did day by day. Saul had his spear in his hand;
"David was playing the lyre, as he did day by day"  (1 Samuel 18:10). Notice that there is no war in progress at this point, giving strong support to the understanding that the preceding celebration that aroused Saul's jealousy came at the termination of an important phase of the Philistine war.