Leviticus 14:1

And the LORD spake unto Moses, saying,

And the Lord spoke to Moses to give the law for the cleansing of one healed of leprosy, with the procedure for that cleansing set out in the verses that follow. Under that law a person with leprosy was regarded as unclean and cut off in isolation from family and from the congregation of Israel. Touching a leper made a person unclean under the law of Moses.

The law required the healed person to present himself to the priest for examination of his condition. The priest had to examine him, confirm complete recovery, and publicly declare and certify him free of the disease. Only after that declaration and certification could he return to home and family, to friends and community and society, and to the congregation of Israel, and only then was his offering accepted. The cleansed person then brought the offering Moses had commanded for his cleansing.

Jesus directed the healed leper to follow this law by showing himself to the priest and bringing the prescribed offering, showing respect for the law given through Moses and that His healing and teaching did not oppose it. That obedience publicly testified to the healing. The healing together with the priests' examination and decision testified to Jesus' divine power and gave the priests evidence of His power and mission.