Was willst du dich betrüben, BWV 107

Johann Sebastian Bach composed the church cantata Was willst du dich betrüben (Why would you grieve), BWV 107 in Leipzig for the seventh Sunday after Trinity and first performed on 23 July 1724. The chorale cantata is based on Johann Heermann's hymn in seven stanzas "Was willst du dich betrüben" (1630).

Bach structured the cantata, the seventh work in his chorale cantata cycle, in seven movements: two framing choral movements, a recitative and an unusual sequence of four bipartite arias. He scored the work for three vocal soloists, a four-part choir, and a Baroque chamber ensemble of a horn to reinforce the hymn tune in the outer movements, two transverse flutes, two oboes d'amore, strings and continuo. It is the only known work from his chorale cantata cycle that kept the original words unchanged.