Jamieson, Fausset and Brown on Esther 7:8

8. Haman was fallen upon the bed whereon Esther was--We do not know the precise form of the couches on which the Persians reclined at table. But it is probable that they were not very different from those used by the Greeks and Romans. Haman, perhaps, at first stood up to beg pardon of Esther; but driven in his extremity to resort to an attitude of the most earnest supplication, he fell prostrate on the couch where the queen was recumbent. The king returning that instant was fired at what seemed an outrage on female modesty.

they covered Haman's face--The import of this striking action is, that a criminal is unworthy any longer to look on the face of the king, and hence, when malefactors are consigned to their doom in Persia, the first thing is to cover the face with a veil or napkin.