Bach's chorale cantata with its opening text 'Wohl dem, der sich auf seinen Gott recht kindlich kann verlassen' (Tis well with him who on the Lord trusts just like a child) BWV 139 was performed for the first time on 12 November 1724 in the main Leipzig church service. The cantata text, based on the hymn of the same name by Johann Christoph Rube (1665-1746), is in praise of trust in God. In the opening chorus, full of depth of feeling, the hymn melody is heard throughout; this is followed by a lively tenor aria 'Gott ist mein Freund' (God is my friend) with a musical depiction of the adversary raging in vain, and in the bass aria 'Das Unglück schlägt auf allen Seiten' (Misfortune assails me on every side) Bach presents both drama and Baroque imagery. One of the two solo violin parts for the tenor aria is lost, so our edition offers a reconstruction. The virtuoso violin part of the bass aria was evidently based on a part for violoncello piccolo, now lost. The edition provides for performance by violin or violoncello.