These men of religion had already suspected
that Jesus was the one involve with this man
who was carrying his bed.

They began to question him as to who it was
that told him to take up his bed and walk.

Notice that they didn't ask who had healed
him. They diliberately ignored the fact but
continued questioning him about carrying
his bed.

The breaking of their law was the only thing
they cared about. They believed that they
had a clear violation of the Law.