Sometimes its there and other times it not?
The problems lay with the early codexes and the writings, so how comes then do we have it!
It had to be added at a later point, but this is not proved either to be true or not, but what is proven is that it contains a more detailed account of Jesus being with His Disciples before His Ascension, filling in the gaps?
Some translations remove some verses in this portion, while others do not have it, but have a footnote at the bottom of the page and this can cause more confusion to the reader than a help!
Luke 24:50-53, Acts 1:6-11.
Happy New year and an peaceful eastern-Christmas to all?