The scribes and Pharisees were offended that a teacher of God would share a table with people they avoided. Gill says they objected to His eating with "men of very infamous characters, and bad lives, with whom the Pharisees disdained to keep company." Gill adds that they were also offended "because he did not fast as they, and their disciples did." A shared meal meant more then than it may seem now. Barnes explains, "To eat and drink with others denotes intimacy and familiarity," so the question was really an accusation (on Matthew 9:11). They put it to the disciples rather than to Jesus. Matthew Henry says, "They endeavoured to put the disciples out of conceit with their Master," that is, to turn them against Him.

The question was put to the disciples, but "when Jesus heard it," He answered for them: "They that are whole have no need of the physician, but they that are sick: I came not to call the righteous, but sinners to repentance" (Mark 2:17). In Matthew's account He also tells them, "go ye and learn what that meaneth, I will have mercy, and not sacrifice" (Matthew 9:13). No reply from the scribes and Pharisees is recorded.

Publicans were tax collectors. Levi had been "sitting at the receipt of custom," the tax booth (Mark 2:14). Matthew Henry notes, "The publicans are here and elsewhere ranked with sinners." Barnes says Levi was "undoubtedly" the same man as Matthew, adding, "It was not uncommon among the Jews to have two names" (compare Matthew 9:9).

Barnes also notes that "The words 'at meat' are not in the original" in Mark 2:15; the phrase means "as he reclined at his meal." The ESV reads "the scribes of the Pharisees," following a Greek text that differs slightly from the one behind the KJV's "scribes and Pharisees."

Jesus' answer explains His whole mission. He came as a physician comes, to the sick. Barnes puts it simply: a physician "would not commonly be found with those that were in health. His proper place was among the sick" (on Matthew 9:12). The scribes and Pharisees saw the publicans as people to avoid. Jesus saw them as people to heal. Matthew Henry, putting Jesus' reply in his own words, writes, "they are sinners, and need a Saviour."

His words also carry a quiet warning. Only those who know they are sick go looking for a physician. Jesus came "to call... sinners to repentance" (Mark 2:17), and the people at that table were the ones answering the call.