Translation of the verse 20 from Surah An-Nazi‘at : Number of verses 46 - - page 584 - Part 30.
Then [Musa (Moses)] showed him the great sign (miracles).
And he showed him the greatest sign,
(79:20) Then Moses (went to Pharaoh and) showed him the Great Sign; *9
*9) "The great Sign" : the turning of the staff into a serpent, as has been mentioned at several places in the Qur'an. Obviously there could be no greater sign than that a lifeless staff should turn into a living serpent right in front of the eyes of the people, that it should devour the artificial serpents produced by the magicians out of their staffs and cords, and vKhen the Prophet Moses should pick it up, it should become a walking stick again. This was proof that it was Allah, Lord of the worlds, Who had sent Moses as a Prophet.
Source : An-Nazi‘at Verse 20: And he showed him the greatest sign,