The first reading is about leprosy. And it’s the backstory for Sunday’s Gospel.
The man who comes to see Jesus in the Gospel is a leper. He followed the steps in the first reading. He went to see the priest. And got the worst possible answer.
Leprosy was incurable, and isolation was the only way to keep it from spreading. The leper who reached out to Jesus was desperate. Without a miracle, he was certain to die. And die alone.
Contact with a leper made you ritually unclean - with good reason, since contacting a leper is a very effective way to get leprosy.
But Jesus' response to the leper is different.
Because Jesus saw the person. Not the label.