Where does "For the kingom the power and the glory are yours now and forever" come from?

I read that Catholics never recited this until fairly recently. In the Bible it is not mentioned at all, so when and why did this line get added to the end of the lords prayer?

It’s found is some Byzantine manuscripts, probably a gloss derived from liturgical use. It’s generally accepted that it is not part of the original text.

I don’t know the truth to it, but my 80 year old mother refers to it as the Protestant addition to the Lords Prayer. Did it start after Vatican 2?

It’s added to the end of the Lord’s Prayer in the King James version and the slightly older Geneva Bible, in Matthew 6:13. I’ve seen it added to the prayer in Russian Orthodox prayer books as well. The phrase is found elsewhere in scripture,

Daniel 2:37
37 You, O king, the king of kings, to whom the God of heaven has given the kingdom, the power, and the might, and the glory,

Psalm 145:11
11 They shall speak of the glory of thy kingdom,
and tell of thy power,

1 Chron 29:11
11 Thine, O Lord, is the greatness, and the power, and the glory, and the victory, and the majesty; for all that is in the heavens and in the earth is thine; thine is the kingdom, O Lord, and thou art exalted as head above all.

Passages taken from the RSVCE

And it is not ‘added’ to the Lord’s Prayer at Mass (although it might look that way). The Lord’s Prayer ends at “and deliver us from evil” as it has always done. The short prayer “for thine is the kingdom and the power and glory” is called a Doxology (an 'acclamation of glory).

This question came up on Catholic radio the other day.

Sourced from the angle that Catholics don’t use the line in the Lord’s Prayer, but others end with it.

The answer given was that the line is originally sourced from the Mass and at some point added in translation to certain versions of the Bible as a part of the Lord’s Prayer by mistake / misunderstanding that it’s not originally the end of the prayer Jesus taught. Rather a conclusion to that part of the Mass.

DISCLAIMER: The views and opinions expressed in these forums do not necessarily reflect those of Catholic Answers. For official apologetics resources please visit www.catholic.com.