A leader who builds his power by humiliating others will ultimately find his cruelty turning back on him. An arrogant ruler who abuses his subjects faces a harsh message of retribution, warned that the cup of disaster he forced others to drink is now making its way to his own lips [ביאור שטיינזלץ]. Commentators offer a few historical identifications for this arrogant figure. It may be directed at Nebuchadnezzar, who loved to humiliate kings and was eventually driven away from human society [רד״ק]. Others identify the ruler as Belshazzar, who drank from the sacred vessels of the Temple specifically to disgrace them [מלבי״ם]. A third perspective views the prophecy as directed at Edom, representing Rome, which destroyed the Second Temple and spilled the blood of the people of Judah [אברבנאל].
The prophecy addresses how this ruler found his greatest pleasure. He derived deep satisfaction and fullness from the very shame he inflicted on others, enjoying their humiliation far more than the actual honor of his military victories [רד״ק, מצודת דוד, אברבנאל]. This feeling of being completely full is specifically connected to the act of drinking [מלבי״ם]. Because he chose to drink for the sake of degrading others, his punishment is to drink from that exact same cup of shame [רד״ק].
As he is forced to drink, three primary approaches describe his resulting downfall. The first approach explains that his defenses will be stripped away and his nakedness exposed for all to see, much like a drunkard who completely loses his human dignity and honor [רד״ק, אבן עזרא, אברבנאל, רש י בשם תרגום יונתן]. A second view suggests an internal collapse, where his heart and mind become completely blocked, leaving him in a state of deep emptiness, astonishment, and confusion [רש״י, מצודת דוד, מצודת ציון]. A third interpretation reads the punishment as a literal cup of deadly poison that he must consume [רד״ק, מלבי״ם, אברבנאל].
The crushing blow finally arrives when this cup of wrath and poison surrounds him, signifying that God Himself is now fighting against the ruler [מצודת דוד, ביאור שטיינזלץ]. In the specific case of Belshazzar, the reference to the right hand of God points directly to the hand of the angel that appeared and wrote his death sentence on the palace wall [מלבי״ם].
The message concludes by continuing the imagery of disastrous drunkenness. Because the punishment is compared to drinking wine until intoxicated, most commentators explain that the final imagery combines the ideas of vomit and shame. Instead of the grand honor the ruler sought, he will find himself covered in and sickened by the vomit of his own disgrace [רד״ק, מצודת דוד, מצודת ציון, מלבי״ם, אבן עזרא]. Another perspective suggests that the language used simply serves to intensify and magnify the sheer power of the shame he will experience [אבן עזרא, אברבנאל]. Ultimately, any false honor he once held will be permanently transformed into absolute disgrace.