The Catechism in Questions & Answers

630. What is the only prayer that is spoken in accordance with a fixed wording in the divine service?

The prayer which Jesus taught is the Lord’s Prayer. It is the only prayer that the believers pray together in accordance with a fixed wording.
One version of it is recorded with five pleas (cf. Luke 11: 2-4), and another, more detailed version is recorded with seven pleas (cf. Matthew 6: 9-13).