13 “Sinners shall fall into his nets”. Not all sinners, certain sinners, who are so great sinners, as to love this life to such a degree as to prefer it to everlasting life, “shall fall into his trap.” But what do you say? Shall they that are such, do you think, fall into his nets? What of Your disciples, O Christ? Behold, when persecution was raging, when they all “left You alone, and went every one to his own:” lo! They who were closest to You, in Your trial and persecution, when Your enemies demanded You to be crucified, abandoned You.
And that bold one, who had promised You that he would go with You even unto death, heard from the Physician what was being done in him, the sick man. For being in a fever, he had said he was whole; but the Lord touched the vein of his heart. Then came the trial; then came the test; then came the accusation; and now, questioned not by some great power, but by a humble slave, and that a woman, questioned by a handmaid, he yielded; he denied thrice....“He wept bitterly,” it says.
Not yet was he fitted to suffer. To him was said, “You shall follow Me afterwards.” Hereafter he was to be firm, having been strengthened by the Lord's Resurrection. Not yet then was it time that those “bones” should be “scattered beside the pit.” For see how many failed, even to those who first hung on His mouth; even they failed. Wherefore? “I am alone, until I pass over:” for this follows in the Psalm....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)