Numbers 28:16

Phase, or Passover, the most solemn of all the festivals, when the lamb was to be eaten on the 15th of Nisan, and during the eight days no leavened bread was allowed. The Jews searched all the corners of their houses, lest some might be concealed by mice, and they would not so much as name it. St. Paul exhorts us to do the like, in a spiritual sense, by purifying ourselves from every defilement of sin when we receive the blessed sacrament, and by not even mentioning sins of impurity, 1 Corinthians v. 7., and Ephesians v. 3. (Haydock)