Those listening to Jesus finally understood his claim to be God (8:58). Because of this, they became very angry. They believed they had heard blasphemy (words that dishonored God) and picked up stones to throw at him, which was the proper legal response (Leviticus 24:16).
Jesus was hidden from them because God had chosen a different time for his death (see study note on John 12:23; see also 7:30, 44; Luke 4:29–30).