Charles Ellicott Commentary Isaiah 23:15

"And it shall come to pass in that day, that Tyre shall be forgotten seventy years, according to the days of one king: after the end of seventy years it shall be unto Tyre as in the song of the harlot." — Isaiah 23:15 (ASV)

Tyre shall be forgotten seventy years. —If we take the number literally, the seventy years may coincide with those of the captivity of Judah, during which, under the Chaldean supremacy, Tyre was reduced to a state of comparative insignificance. It seems better, however, with Cheyne, to take it as a symbolic number for a long period of indefinite duration, and so, bringing it into closer connection with the context, to reckon the period from its conquest by the Assyrians.

According to the days of one king. —We look in vain for any ruler of Assyria or Babylon whose reign was of this length, and the words probably mean, as the days fixed by a king — that is, by a despotic and absolute decree. Possibly, however, the “one king” may stand for one dynasty.

Shall Tyre sing as an harlot. —Literally, there shall be to Tyre as the song of the harlot, possibly referring to some well-known lyric of this type. The commercial city, welcoming foreigners of all nations as her lovers for the sake of gain, is compared to the prostitute who sells herself for money .