This cantata (you can find streaming recordings, a score of sorts, the text, and English translation at bach-cantatas.org) was not composed for any “special” day, and yet it displays great imagination and variety from the Bach’s standard cantata formulae. He wrote it in 1724, his second year at Leipzig, a year where he only wrote cantatas.
On the Sunday it was first “performed,” the NT reading was the story of Jesus meeting Peter, who had not caught any fish the previous night. Jesus told him to cast his nets on the other side, and their net was filled with fish to overflowing. We should always let God guide us and He will be good to us. So Bach used for chorale basis of the cantata the German hymn text Wer nur den lieben Gott läßt walten, written by Georg Neumark in 1657. The libretto for the cantata takes the hymn text and works freely with it, often adding a kind of commentary. I recommend that before listening to the entire cantata that you listen to the chorale (from this recording) a few times so that you can recognize it as Bach returns to it in each movement throughout the work.
The opening movement leaves Neumark’s text unchanged. Each line is written twice, the first being a freely set duet (except in the last two lines), the second being a four-part chorale with the soprano seeing the chorale tune and text above and the three voices below developing the lines of the duet in the first part. In the last two lines, the first singing of the chorale text is done by a quartet. Throughout all of this the orchestra is freely playing a “concerto-like” setting below.
A bass recitative follows where Bach sets musically many of the phrases the bass sings. You will notice that he sings chorale lines four times, and adding "comments" after each one. Bach sets each line from the hymn with the chorale tune that goes with it.
The third movement is “laid back” and “resting,” but is still connected in many ways to the original hymn. The text uses two lines from the hymn (lines one and three). The beginning phrase played by the violins is nothing but the chorale tune in a major key with a pause after two measures to reflect the first line, “Man halte nur ein wenig stille”– "if we be but a little quiet.”
The fourth is the central movement, and Bach, one always symmetrically structuring things, again uses a complete verse of the hymn text, just like in the beginning and ending movements. The tune is not being sung, yet the resulting duet is free and polyphonic. Meanwhile, the strings play the hymn tune somewhat conspicuously below, perhaps highlighting the fifth line, " So kömmt Gott, eh wir uns versehn," — "Then God comes, e'en before we know." Schweitzer uses the bass line as an example of a “motif of joy” (J. S. Bach 2:112).
The recitative in the fifth movement is much like the 2nd movement. A few lines of the hymn text interpreted with free verse besides. The music again plays a role musically depicting the text.
The sixth movement is a sprightly and joyful verse, and not seeming to resemble much the original text or tune. Yet Bach still finds a way of writing in a line from the hymn, with the original tune, no less! Listen careful when the soprano sings, Er ist der rechte Wundersmann and Nach seinem Willen machen kann. Bach concludes the cantata as he does so many, returning to the original chorale.