After David killed Goliath, and the women began singing his praises, it caused King Saul to be jealous of David. And because of his jealousy,

1 Samuel 17:47 And all this assembly shall know that the LORD saveth not with sword and spear: for the battle is the LORD’S, and he will give

1Timothy 6:12 Fight the good fight of faith, lay hold on eternal life, whereunto thou art also called, and hast professed a good profession before many