1 Samuel 18:10
And it came to pass on the morrow, that the evil spirit from God came upon Saul, and he prophesied in the midst of the house: and David played with his hand, as at other times: and there was a javelin in Saul’s hand. And it came to pass on the morrow, that the evil spirit from God came upon Saul, and he prophesied in the midst of the house: and David played with his hand, as at other times: and there was a javelin in Saul’s hand.
Saul was under the control of the evil spirit, governed by jealousy and hatred toward David and yielding to a cruel spirit of jealousy. God had left Saul to his guilty course. His was a marked character combining strength and weakness, with contradictory elements bound up in him working at cross purposes with God, good and evil ever in collision in him and evil ever striving for supremacy. Gifts of talent had been bestowed upon him, and had he consecrated them wholly to God he would not have dishonored himself by his own transgression.
At times he showed marked simplicity and was very tender and full of sympathy toward those who pleased him, and then he displayed a jealous and overbearing spirit and was unjust and cruel toward his best friends. When brought under the influence of sacred vocal music and the singing of praises to God, he caught the spirit of devotion and the evil spirit was quieted for a time. His prophesying in the house consisted of pouring forth impassioned expressions of lofty eloquence in ecstasies of praise and prayer, giving himself no rest day nor night until the reaction came and his strength failed in exhaustion. David was a righteous man chosen by the Lord to save Israel.
David played before Saul as at other times, as usual, to soothe his troubled mind. Then Saul suddenly hurled his sharp-pointed javelin or spear at David, aiming at his heart, with intent to kill him. God preserved David through angels: David understood and saw Saul's purpose, sprang aside and fled unharmed, while the weapon struck the wall where he had been sitting.
When the paroxysm of wild excitement and inordinate zeal had spent itself, Saul revealed his old disposition, and when his will was crossed he broke into fury in words and deeds entirely dishonoring to himself and still more dishonoring to God. By acting as a murderous ruler in trying to kill David, Saul showed Israel how far a king who rebelled against God and followed his own passions might go.