In the last long trimeter speech of the Prometheus Vinctus Hermes describes to Prometheus the future course of his punishment: he will be swallowed up in the earth, and then after a long interval of time brought back to daylight for laceration by Zeus's eagle. Hermes goes on (1026 ff.):

The only substantial variant is θεός τις F Tri. in 1027.

There is no proof that ancient critics saw any definite allusion here. The Medicean scholium is simply ( Paley) πεισομένου, an obscure note to which I shall return. Matthias Garbitius (1559), the first scholar quoted by S. Butler in his variorum edition of 1809, suggested that the reference was either to Hercules or, more probably, to ‘some other hero’ destined to free the human mind from darkness and doubt, perhaps a Sibylline vision of the Christian redemption. This last fancy was defended anonymously in the Gentleman's Magazine for 1796 and found a belated champion in F. A. Paley, on the eve of his admission to the Church of Rome, in 1846—‘Ceterum venturum esse Messiam et descensurum in inferos antiquitus praedictum quis hic non agnoscit?’ Later Paley silently dropped this theory.