“He answered them, I have told you already, and ye did not hear: wherefore would ye hear it again? will ye also be his disciples?”
John 9:27 — Greek Interlinear
Church Fathers on John 9:27
The parents having referred the Pharisees to the healed man himself, they summon him a second time: Then again called they the man that was blind. They do not openly say now, Deny that Christ has healed you, but conceal their object under the presence of religion: Give God the praise, i.e. confess that this man has had nothing to do with the work.
Deny that you have received the benefit. This is not to give God the glory, but rather to blaspheme Him.
The man, that he might neither expose himself to calumny, nor at the same time conceal the truth, answers not that he knew Him to be righteous, but, Whether He is a sinner or no, I know not.