Not one jot or tittle passed away

I just realized why Jesus told the leper to show himself to the priest and offer the sacrifice that Moses commanded. Showing himself to the priest would be necessary for others to be able to accept him as clean (I already knew that) but going before the priest and offering the required sacrifice were each required under the Law of Moses which was still in force. The leper had been healed regardless of whether he had done this things but doing this things was necessary in order to be right with that law.