42. This is capable of two interpretations:
(1) The staff, which was turned into a dragon by a miracle, actually swallowed up all the staffs and cords which had been made to appear as serpents.
(2) The dragon of the staff did not actually swallow up the serpents of the magicians but wiped out the effect of their magic from these things and they again became ordinary cords and staffs.
We prefer the second interpretation because the wording of (Surahs Al-Aaraf, Ayat 117) and (Ash-Shuara, Ayat 45) is this: It swallowed up their false magic. And here the wording is: It will swallow up what they have crafted. Obviously, the staffs and cords were not their creation but the magic which had made them appear like serpents.