A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
est 7:4ESTHER PLEADS FOR HER OWN LIFE AND THE LIFE OF HER PEOPLE. (Est 7:1-6)
we are sold, I and my people, to be destroyed--that is, by the cruel and perfidious scheme of that man, who offered an immense sum of money to purchase our extermination. Esther dwelt on his contemplated atrocity, in a variety of expressions, which both evinced the depth of her own emotions, and were intended to awaken similar feelings in the king's breast.
But if we had been sold for bondmen and bondwomen, I had held my tongue--Though a great calamity to the Jews, the enslavement of that people might have enriched the national treasury; and, at all events, the policy, if found from experience to be bad, could be altered. But the destruction of such a body of people would be an irreparable evil, and all the talents Haman might pour into the treasury could not compensate for the loss of their services.
est 7:7THE KING CAUSES HAMAN TO BE HANGED ON HIS OWN GALLOWS. (Est 7:7-10)
he saw that there was evil determined against him by the king--When the king of Persia orders an offender to be executed, and then rises and goes into the women's apartment, it is a sign that no mercy is to be hoped for. Even the sudden rising of the king in anger was the same as if he had pronounced sentence.
est 7:8Haman 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.
est 7:9Harbonah, one of the chamberlains, said before the king, Behold also, the gallows--This eunuch had probably been the messenger sent with the invitation to Haman, and on that occasion had seen the gallows. The information he now volunteered, as well it may be from abhorrence of Haman's cold-blooded conspiracy as from sympathy with his amiable mistress, involved with her people in imminent peril.
est 7:10So they hanged Haman on the gallows that he had prepared for Mordecai--He has not been the only plotter of mischief whose feet have been taken in the net which they hid (Psa 9:15). But never was condemnation more just, and retribution more merited, than the execution of that gigantic criminal.