Charles Ellicott Commentary 1 Samuel 18:10

"And it came to pass on the morrow, that an evil spirit from God came mightily upon Saul, and he prophesied in the midst of the house: and David played with his hand, as he did day by day. And Saul had his spear in his hand;" — 1 Samuel 18:10 (ASV)

The evil spirit. The evil spirit now comes over the unhappy king in quite a new form. Previously, when the dark hour came upon Saul, the madness showed itself as a dull torpor, a hopeless melancholy, and an entire indifference to everything connected with life, in both its lower and higher forms. This earlier phase of the soul’s malady has been exquisitely pictured by Browning in his poem “Saul.”

Now the madness assumes a new phase: the king is consumed with a murderous jealousy that fills his whole soul, driving him, now to open deeds of ruffianly violence, now to devise dark plots against the life of the one he targeted. What a fall for the hero-king of Israel, the anointed of the Lord, whose reign had begun so brilliantly and successfully!

And he prophesied. In his wild frenzy—under the control of a power higher than himself (for had he not, by breaking off all communion with God, left his soul defenseless and prepared for the presence of the evil spirit?)—we read that Saul prophesied.

The Dean of Canterbury well calls attention here to the conjugation employed in the original Hebrew for the word rendered “prophesied”: the Hith-pael, which is never used by an Old Testament writer of real true prophecy, as this is always expressed by the Niphal conjugation.

This prophesying of Saul’s was but a spurious imitation.

Saul was in a state of frenzy, unable to control himself, speaking words whose meaning he did not know, and acting like a man possessed. In all this there was something similar to the powerful emotions that agitated the true prophet; only it was not a holy influence, but one springing from violent passions.