The Pharisees saw nothing funny in the man"s reply, however. They were deadly serious in their attempt to execute Jesus. They undoubtedly realized that this former beggar had seen through their veiled attempt to condemn Jesus unjustly. They met his good-natured prod with insult. They turned his charge back on himself and presented following Jesus as irreconcilable with following Moses. Of course, the Pharisees were not the disciples of Moses that they claimed to be. Ironically, Jesus was. Failure to know where Jesus came from amounted to failing to know where He received His authority. Moses had come from God, but Jesus" critics claimed not to know whether He came from God or from Satan ( John 9:16). Most of them suspected the latter. [source][source][source]
"The Pharisees were cautious men who would consider themselves conservatives, when in reality they were "preservatives."... A "preservative" simply embalms the past and preserves it. He is against change and resists the new things that God is doing." [1][source]
We see here an essential difference between Judaism and Christianity (cf. John 1:17). The Jews continue to profess allegiance to Moses as the Pharisees did here while Christians claim to follow Jesus, which is what they charged the restored man with doing. Following Jesus involves accepting Moses" revelation as authoritative since Jesus authenticated Moses" writings. [source][source][source]
Earlier Jesus" enemies said they knew where He came from, namely, Galilee ( John 7:27). They were wrong in their assessment of Jesus" earthly origin as they were wrong about His heavenly origin. Here they were speaking of His authoritative origin, specifically who had sent Him. [source][source][source]