Page "Mass in B minor" Paragraph 8

The performance material Bach submitted to Augustus on July 27, 1733 was written on Dresden-made paper, in the hand of Bach, his wife Anna Magdalena, sons Wilhelm Friedemann and Carl Philipp Emanuel, and a Dresden copyist.

This suggests the piece was written out in Dresden by the Bach family for a July performance in the Sophienkirche ( where Wilhelm Friedemann was organist ), or perhaps the Hofkirche im Theater.