1 The title of this Psalm has fruit in the prolixity thereof, if it be understood: and because the Psalm is short, let us make up our not having to tarry over the Psalm by tarrying over the title. For upon this depends every verse which is sung. If any one, therefore, observe that which on the front of the house is fixed, secure he will enter; and, when he shall have entered, he will not err. For this on the post itself is prominently marked, namely, in what manner within he may not be in error.
The title thereof stands thus: “At the end, in hymns, understanding to David himself, when there came the Ziphites, and said to Saul, Behold, is not David hidden with us?” That Saul was persecutor of the holy man David, very well we know: that Saul was bearing the figure of a temporal kingdom, not to life but to death belonging, this also to your Love we remember to have imparted. And also that David himself was bearing the figure of Christ, or of the Body of Christ, you ought both to know and to call to mind, you that have already learned. What then of the Ziphites?
There was a certain village, Ziph, whereof the inhabitants were Ziphites, in whose country David had hidden himself, when Saul would find and slay him. These Ziphites then, when they had learned this, betrayed him to the king his persecutor, saying, “Behold, is not David hidden with us?” Of no good to them indeed was their betrayal, and to David himself of no harm. For their evil disposition was shown: but Saul not even after their betrayal could seize David; but rather in a certain cave in that very country, when into his hands Saul had been given to slay, David spared him, and that which he had in his power he did not. But the other was seeking to do that which he had not in his power.
Let them that have been Ziphites take heed: let us see those whom to us the Psalm presents to be understood by the occasion of those same men.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)