They were using this question as a trap, in order to have a basis for accusing him. But Jesus bent down and started to write on the ground with his finger.
NIV
This they said to try (test) Him, hoping they might find a charge on which to accuse Him. But Jesus stooped down and wrote on the ground with His finger.
AMP
This they said, tempting him, that they might have to accuse him. But Jesus stooped down, and with his finger wrote on the ground, as though he heard them not.
KJV
They still did not believe that he had been blind and had received his sight until they sent for the man's parents.
NIV
However, the Jews did not believe that he had [really] been blind and that he had received his sight until they called (summoned) the parents of the man.
AMP
But the Jews did not believe concerning him, that he had been blind, and received his sight, until they called the parents of him that had received his sight.
KJV