"for thine is the kingdom, the power and the glory for ever and ever" - where did this come from?

Well, it's actually part of the prayer in a way but it's not commonly used. I'm Catholic but at mass when we recite the Out Father or considered to be Lord's Prayer we end it with "And Lead us not into temptation but deliver us from evil". In real life, it just ends there - but in mass once we're done saying Our Father, we say "for the kingdom, the power and the glory are Yours now and forever".