The String Quartet No. 3 in B flat major, Op. 67, was composed by Johannes Brahms in the summer of 1875 and published by the firm of Fritz Simrock. It received its premiere performance on October 30, 1876 in Berlin. The work is scored for two violins, viola, and cello, and has four movements:
Brahms composed the work in Ziegelhausen, near Heidelberg, and dedicated it to Professor Theodor Wilhelm Engelmann, an amateur cellist who had hosted Brahms on a visit to Utrecht. Brahms was at the time the artistic director of the Vienna Gesellschaft der Musikfreunde. The work is light-hearted and cheerful, "a useless trifle," as he put it, "to avoid facing the serious countenance of a symphony", referring to the work on his first symphony which debuted a week later.
The irony to this quartet is that although the quartet is dedicated to Engelmann, who is a cellist, in the third movement, the Agitato, the melody of the movement is mainly played by a viola instead of the cello. In a letter about the quartet to Engelmann, Brahms said 'This quartet rather resembles your wife—very dainty, but brilliant! ...but of simply standing by. There’s no cello solo in it, but such a tender viola solo that you may want to change your instrument for its sake!'. By doing this, since Brahms favor mid-range instruments and is aware of the viola's low popularity, he was hoping that Engelmann would switch from cello to viola to support the viola's popularity from neglect, by muting all of the other string instruments so that the viola's sound can be heard.