1 Every one who faithfully reads the Acts of the Apostles, acknowledges that this Psalm contains a prophecy of Christ; for it evidently appears that what is here written, “let his days be few, and let another take his office,” is prophesied of Judas, the betrayer of Christ....For as some things are said which seem peculiarly to apply to the Apostle Peter, and yet are not clear in their meaning, unless when referred to the Church, whom he is acknowledged to have figuratively represented, on account of the primacy which he bore among the Disciples; as it is written, “I will give unto you the keys of the kingdom of heaven,” and other passages of the like purport: so Judas does represent those Jews who were enemies of Christ, who both then hated Christ, and now, in their line of succession, this species of wickedness continuing, hate Him. Of these men, and of this people, not only may what we read more openly discovered in this Psalm be conveniently understood, but also those things which are more expressly stated concerning Judas himself.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)