Herz und Mund und Tat und Leben, BWV 147.1, BWV 147a, is a cantata by Johann Sebastian Bach. He composed it in Weimar in 1716 for the fourth Sunday in Advent, 20 December. It is uncertain if the work was performed then. He later expanded the work in 1723 as Herz und Mund und Tat und Leben, BWV 147.