The painting is a generalised Arcadian scene. Its only connection with the biblical story of Isaac and Rebecca is Claude's inscription on the tree stump in the centre of the picture. Another version of this painting without the inscription is called 'The Mill' (now in the 'Palazzo Doria Pamphilij' in Rome).
The Duc de Bouillon, general of the Papal army, commissioned Claude to paint both this painting and the 'Seaport with the Embarkation of the Queen of Sheba' in 1647 and they were completed the following year.
The pictures complement each other, showing joyful and fulfilling occasions taken from Old Testament stories. Seaport with the Embarkation of the Queen of Sheba is a port scene and the Marriage of Isaac and Rebecca takes place inland.
Claude's use of trees to frame the action is typical of his work, as is his giving the composition an overall balance.
Both this painting and its pair were among the pictures owned by the Gallery when it first opened in 1824. The painting was purchased from the Angerstein collection.
From The National Gallery Podcast: Episode Forty, February 2010