12 Saul then having made this declaration, the people were more afraid than before, and all were in a state of great trembling and terror. But the devil rejoiced, at having rendered them all thus anxious. There was no one, we are told, of all the people, who answered. “And Saul said, You will be in bondage, and I, and Jonathan my son, will be in bondage.” But what he means is to this effect; “You are aiming at nothing else, than to deliver yourselves to your enemies, and to become slaves instead of free men; while you provoke God against you, in not delivering up the guilty person.”
Observe also another contradiction produced by the oath. It had been fitting, if he wished to find the author of this guilt, to have made no such threat, nor to have bound himself to vengeance by an oath; that becoming less afraid, they might more readily bring the offender to light. But under the influence of anger, and great madness, and his former unreasonableness, he again does that which is directly contrary to what he desires. What need is there to enlarge? He commits the matter to a decision by lot; and the lot falls upon Saul, and Jonathan; “And Saul said, Cast ye the lot between me and Jonathan; and they cast the lot, and Jonathan was taken.
And Saul said to Jonathan, Tell me, what have you done? And Jonathan told him, saying, I only tasted a little honey on the top of the rod which is in my hand, and, lo! I must die.” Who is there that these words would not have moved and turned to pity? Consider what a tempest Saul then sustained, his bowels being torn with anguish, and the most profound precipice appearing on either hand! But nevertheless he did not learn self-control, for what does he say? “God do so to me, and more also; for you shall surely die this day.” Behold again the third oath, and not simply the third, but one with a very narrow limit as to time; for he does not merely say, “You shall die;” but, “this day.” For the devil was hurrying, hurrying him on, constraining him and driving him to this impious murder.
Wherefore he did not suffer him to assign any future day for the sentence, lest there should be any correction of the evil by delay. And the people said to Saul, “God do so to us, and more also, if he shall be put to death, who has wrought this great salvation in Israel. As the Lord lives, there shall not an hair of his head fall to the ground; because he has wrought a merciful thing from God today.” Behold how, in the second place, the people also swore, and swore contrary to the king.
Source: Homilies on the Statues (New Advent)