CCC 1454 The reception of this sacrament ought to be prepared for by an examination of conscience made in the light of the Word of God. The passages best suited to this can be found in the Ten Commandments, the moral catechesis of the Gospels and the apostolic letters, such as the Sermon on the Mount and the apostolic teachings.1
1 Cf. Mt 5-7; Rom 12-15; 1 Cor 12-13; Gal 5; Eph 4-6; etc.