“So Haman took the robes and the horse. He robed Mordecai. He led him riding through the open square of the city, proclaiming,
‘Thus shall it be done to the man whom the king wishes to honor.’
Then Mordecai returned to the king’s gate.”
Then Haman had to bring Mordecai around the city into the open square. Haman had to proclaim that this is the man who the king wishes to honor. He, the one who hated Mordecai, was now his servant leading Mordecai with the royal robes and royal horse.