Lest mine enemy say, I have prevailed against him. The triumph of David's enemy over him, whether he were Saul or any one else, even the ideal wicked man, would be the triumph of evil over good, of those who had cast God behind their back over those who faithfully served him, of irreligion over piety.
He could therefore appeal to God—not in his own personal interest, but in the interest of truth and right, and the general good of mankind—to prevent his enemy's triumph. And those that trouble me rejoice when I am moved.
There would be a general rejoicing on the part of all his foes, if his arch-enemy succeeded in seriously injuring him.