There is a fairly uniform text for Kiddush Friday night. There are some differences between the Ashkenazi and Sfardi versions, but they are mostly very similar.
What is the source for the text? As far as I know, it isn't in the Talmud anywhere. The Tur comments on certain phrases, but he doesn't include the text of the bracha; neither do the Beit Yosef or the Bach.
So where can I find the earliest version?