Catechism of the Catholic Church 350:
Angels are spiritual creatures who glorify God without ceasing and who serve his saving plans for other creatures: “The angels work together for the benefit of us all” (St. Thomas Aquinas, STh I, 114, 3, ad 3).
God, you have given me a guardian angel to free me, to lead me away from fear, to lead me away from misfortune. In return, you ask only that I listen to him and respect him.
Help me to have a docile and open heart, that I might listen to my angel. May this docility to my angel lead me to an ever greater docility to your Holy Spirit. This is the docility that makes me truly great and leads me to heaven.
Thank you for sending me this ambassador in your name, this ever present companion who supports me and leads me on the path to heaven.
(Cf. Pope Francis, morning homily, October 2, 2015).