The pronoun he refers to Jesus. Some translators use the proper noun, “Jesus.”

Heard it: the Greek text does not indicate the object of the verb heard, but English structure requires one. New English Bible and Die Bibel im heutigen Deutsch follow Revised Standard Version in supplying it (New Jerusalem Bible “this”), with the question of the Pharisees as the antecedent. New American Bible has “Overhearing the remark.” Good News Translation provides “them,” which is actually an abbreviated form for “… them say this” or “… them ask this question.” For some languages it may be necessary to be even more specific: “heard the question of the Pharisees” or “heard the Pharisees ask his disciples this question.”

Jesus’ reply takes the form of a parable in which tax collectors and other sinners (verse 10) are described as those who are sick.

Those may need to be rendered “those people” or “people.” The sentence can be translated “People who aren’t sick (or, People who are healthy) don’t need a doctor, only sick people do.” The order can also be reversed, as in “It is sick people who need a doctor, not those who are healthy.”

Quoted with permission from Newman, Barclay M. and Stine, Philip C. A Handbook on the Gospel of Matthew. (UBS Handbook Series). New York: UBS, 1988. For this and other handbooks for translators see here .