Mark says Christ strictly warned the healed leper: "Say nothing to anyone." He was to show himself to the priest and offer the prescribed gift as a witness of what Jesus had done. By showing himself to the priest, the healed leper fulfilled the requirement of the law as to his fitness to return to social life (Leviticus 13:17). As far as we know, this was the first case of an Israelite leper being cleansed since the instructions given nearly 1,500 years before (Leviticus 13:34). The appearance of a cleansed leper at the altar with his gift in his hand testified that God had come to His people and totally satisfied priestly requirements and ordinances.
Yet, this man allowed his zeal to overrule good judgment and obedience to his Healer's command. In fact, his self-absorption in broadcasting his healing seriously impeded Christ's work. Due to the leper's spreading of his news, large numbers of lepers in the region pursued Jesus relentlessly for healing. Thus, "Jesus could no longer openly enter the city, but was outside in deserted places; and they came to Him from every direction" (Mark 1:45; Luke 5:15-16). However, it was not His purpose to heal all of Israel then but to reveal the Father and His relationship with Him. Being sensational does not mean we make a better testimony for Christ. Rather, this incident illustrates that, generally, the obedient person whom only a few know about makes the better-quality witness.
Martin G. Collins
The Miracles of Jesus Christ: Healing a Leper (Part Three)