Bach’s authorship of this piece is uncertain, hence its catalogisation in Anhang II of Schmieder’s Bachwerke Verzeichnis. Two sources for this piece are available online. Though it’s clearly the same piece, both sources differ in lots of details. The one from manuscript Mus. Hs. 35149, available at the Östereichische Nationalbibliothek seems to me the older version, perhaps even the ‘original’. The version available at the Bach Archiv Leipzig (D-LEb Rara Ib, 45) is a more embellished version (the one that's recorded in this video). It is like someone wrote out how an experienced player could spontaneously add al sorts of details while playing the simple version from Mus. Hs. 35149. Though Bach’s authorship is uncertain, it is nevertheless an elegantly constructed piece. The first phrase of the choral melody is first the basis of a four voice fugue. After that the choral melody is played in the pedal, accompanied by fast moving figures in the hand. Each phrase of the choral melody is foreshadowed in the soprano voice.
Source: Partitura Organum, who delivered this nice score freely to us.
What do you think: Bach or not?
Played with a big plenum on the Hauptwerk sample set of the Marcussen organ (1973) of the Laurenskerk, Rotterdam. I used stops from the Hoofdwerk and the romantic Bovenwerk, which isn't obvious for baroque pieces, but it works out nicely I think.