“Jesus answered them.
He told them.
All of you
ἀπεκρίθη Ἰησοῦς καὶ εἶπεν αὐτοῖς Ἓν ἔργον ἐποίησα καὶ πάντες θαυμάζετε.
John uniquely indicated that Jesus (Ἰησοῦς) answered (ἀπεκρίθη) them. He told them (καὶ εἶπεν αὐτοῖς) that he had performed one work (Ἓν ἔργον ἐποίησα) that astonished all of them (καὶ πάντες θαυμάζετε). That was in chapter 5:1-9, when he cured the lame person on the Sabbath at the Sheep Gate pool. Unlike the synoptics, Jesus did not do a series of faith healings or cures. Instead there had been so far just the miracle at Cana and the healing of the man who had been ill for 38 years. They were astonished then, but why were they so critical now? Are you too critical of people?