In this artwork, how is the Commission discussed?
Saint Matthew and the Angel was created  as a commission for the Contarelli Chapel. Caravaggio was previously commissioned to paint two scenes of the saint's life, and after the patrons were satisfied with them, a third was commissioned.
The Contarelli Chapel was dedicated to Saint Matthew. With funds left for its building in 1585, it was completed in 1600. Cardinal Del Monte played a major part in orchestrating the decoration of its interior, and was the one who suggested Caravaggio as the painter of the scenes of Saint Matthew's life. The altar was to be composed of two Caravaggio paintings as well as a statue of the saint by Flemish artist Jacob Cobaert.  However, the church was not pleased with the statue and Caravaggio was re-hired to do another piece as the center for the altar, to show Saint Matthew writing the Gospel under the guidance of an angel. Caravaggio depicted the Saint as an unlearned peasant, gaping in the presence of the angel. The church rejected Caravaggio's irreverent presentation of the saint, and Caravaggio replaced it with a more glorifying image, The Inspiration of Saint Matthew, which remains in the Chapel today.
Saint Matthew The Inspiration of Saint Matthew Angel Caravaggio Gospel Jacob Cobaert dedicated angel Contarelli Chapel