The reason why his parents answered so very warily, and avoided saying any thing to the Pharisees third question, which probably they could not go of their particular personal knowledge, was, that they were afraid of the rulers of the Jews. Solomon saith, The fear of man bringeth a snare, Proverbs 29:25; it is often a temptation to men to deny the truth, or, at least, not to own and confess it when God calls to them for a public owning and confession of it: but nothing of that nature appeareth in this case; for it doth not appear that his parents were present when Christ wrought this great miracle; which if they were not, they were not obliged to tell the Pharisees what themselves had only received by rumour and hearsay: so that their answer seems but a prudential answer, to avoid an eminent danger. For they were not ignorant of a decree made by the Jewish sanhedrim. That if any did publicly say, or declare, that Jesus was Christ, he should be excommunicated; for that is meant by being put out of the synagogue.
Related Commentaries of John 9:22
John 9:22
22 These words spake his parents, because they feared the Jews: for the Jews had agreed already, that if any man did confess that he was Christ, he should be put out of the synagogue.