This is a profound chorale prelude by Bach, based on the hymn tune 'An Wasserflüssen Babylon'. It is notable for its rich contrapuntal texture and its deeply expressive harmonic language.
Mastering the independent melodic lines and achieving a clear, balanced voicing is crucial.
An Wasserflüssen Babylon (BWV 653b) is rated Henle level 6 of 9 — advanced repertoire, roughly ABRSM grades 7–8. In the RCM system it corresponds to about level 9.
You should be comfortable at Henle level 6 — meaning you can already play level 5–6 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of An Wasserflüssen Babylon (BWV 653b) lasts about 6 minutes.
An Wasserflüssen Babylon (BWV 653b) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.