Bede the Venerable — as excerpted in the Catena Aurea on Mark 2:13-17

“(ubi sup.) If by the election of Matthew and calling of the publicans, the faith of the Gentiles is expressed, who formerly were intent on the gains of this world; certainly the haughtiness of the Scribes and Pharisees intimates the envy of the Jewish people, who are vexed at the salvation of the Gentiles. It goes on: When Jesus heard it, he saith unto them, They that are whole need not the physician, but they that are sick. He aims at the Scribes and Pharisees, who, thinking themselves righteous, refused to keep company with sinners. He calls Himself the physician, Who, by a strange mode of healing, was wounded on account of our iniquities, and by His wound we are healed. And He calls those whole and righteous, who, wishing to establish their own righteousness, are not subject to the righteousness of God. Moreover He calls those rich and sinners, who, overcome by the consciousness of their own frailty, and seeing that they cannot be justified by the Law, submit their necks to the grace of Christ by repentance. Wherefore it is added, For I came not to call the righteous, but sinners, &c.”