Catechism of the Catholic Church §1973 — excerpt
Besides its precepts, the New Law also includes the evangelical counsels. the traditional distinction between God's commandments and the evangelical counsels is drawn in relation to charity, the perfection of Christian life.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: St. Thomas Aquinas, STh II-II, 184, 3