The source for this composition is manuscript Mus.ms. Bach P 1115, owned by the Staatsbibliothek Berlin. It contains 12 compositions of which the authorship of Bach is undisputable. Besides these 12 compositions, it contains two more choral preludes to the choral "Schmücke dich, o liebe Seele". The first of these two is in other manuscripts attributed to Gottfried August Homilius. The second of these two choral preludes is not found in another extant manuscript, so it remains uncertain who the author is. It could be Bach, but it could Homilius as well. Or a totally different composer.
Regardless of who composed it, it is a fun piece to play. The choral melody is given a richly embellished accompaniment, that fit well the first words of the text. Intruiging is that only the first two lines of the choral melody are heard in the composition. It could be a nice project to try and extend the composition to incorporate the remaining lines of the choral melody as well.