Then Musa showed him a great sign.
He then showed him the great miracle
He showed him the mighty sign
So he showed him the mighty sign
So he showed him/made him understand the verse/evidence/sign, the greatest/biggest
…. you will be at awe with His Might.”
So Moosa showed him a magnificent sign
So he showed him the great Sign
Then Musa (Moses) showed him the great sign
So (Moses went to Pharaoh and) he showed him the great sign (of the staff)
Then (Moosa (Moses)) showed him the great sign (miracles)