en.wikipedia.org/wiki/Lord%27s_Prayer
"The square brackets in three of the texts below indicate the doxology often added at the end of the prayer by Protestants and, in a slightly different form, by the Byzantine Rite ("For thine is the kingdom and the power and the glory: of the Father, and of the Son, and of the Holy Spirit, now and ever, and unto ages of ages. Amen."[14]), among whom the prayer proper is usually recited by the cantors and congregation in unison, and the doxology by the priest as the conclusion of the prayer. The Anglican Book of Common Prayer adds it in some services but not in all. Older English translations of the Bible, based on late Byzantine Greek manuscripts, included it, but it is excluded in critical editions of the New Testament, such as that of the United Bible Societies. It is absent in the oldest manuscripts and is not considered to be part of the original text of Matthew 6:9–13. The Catholic Church has never attached it to the Lord's Prayer, but has included it in the Roman Rite Mass as revised in 1969, not as part of the Our Father but separated from it by a prayer called the embolism spoken or sung by the priest (in the official ICEL English translation: "Deliver us, Lord, we pray, from every evil, graciously grant peace in our days, that, by the help of your mercy, we may be always free from sin and safe from all distress, as we await the blessed hope and the coming of our Saviour, Jesus Christ.") that elaborates on the final petition, "Deliver us from evil." For more information on this doxology, see Doxology, below. When Reformers set out to translate the King James Bible, they assumed that a Greek manuscript they possessed was ancient and therefore adopted the phrase "For thine is the kingdom, the power, and the glory forever" into the Lord’s Prayer. Later scholarship demonstrated that the manuscript was actually a late addition based on Eastern liturgical tradition."