Mark 1: (KJV)
40 “And there came a leper to him, beseeching him, and kneeling down to him, and saying unto him, If thou wilt, thou canst make me clean. 41 And Jesus, moved with compassion, put forth his hand, and touched him, and saith unto him, I will; be thou clean.”
Numbers 5: (JPS)
1 “And HaShem spoke unto Moses, saying: 2 'Command the children of Israel, that they put out of the camp every leper, and every one that hath an issue, and whosoever is unclean by the dead; 3 both male and female shall ye put out, without the camp shall ye put them; that they defile not their camp, in the midst whereof I dwell.'”
Hardly anyone of our time would criticize Jesus for trying to heal a leper and most people would even applaud his effort.
However, touching a leper would be a violation of the Hebrew bible's law (Leviticus 13) and Jesus previously stated in “Matthew” that he did not come to make any changes to the Law.