Albert Barnes Commentary Esther 6:8

"let royal apparel be brought which the king useth to wear, and the horse that the king rideth upon, and on the head of which a crown royal is set:" — Esther 6:8 (ASV)

The honors here proposed by Haman were such as Persian monarchs rarely allowed to subjects. Each act would have been a capital offence if done without permission. Still, we find Persian monarchs allowing their subjects in these or similar acts under certain circumstances.