"For, amen I say to you, if you have faith as a grain of mustard seed, you shall say to this mountain: Remove from hence hither, and it shall remove: and nothing shall be impossible to you." Matthew 17:

Catechism of the Catholic Church
http://www.usccb.org/beliefs-and-teachings/what-we-believe/catechism/us-catholic-catechism-for-adults/