There was a pool in Jerusalem that had periods of disturbed waters, probably caused by irregular flow from a spring. The people thought that an angel went in at a certain time and stirred the water. They believed that the first sick person who got into the water at that time would be healed of his disease.
As Jesus arrived to observe the feast, He went to this pool and saw a man who had been lame for thirty-eight years. He healed the man, but it was on the Sabbath.