Charles Ellicott Commentary Isaiah 23:18

"And her merchandise and her hire shall be holiness to Jehovah: it shall not be treasured nor laid up; for her merchandise shall be for them that dwell before Jehovah, to eat sufficiently, and for durable clothing." — Isaiah 23:18 (ASV)

Her merchandise and her hire shall be holiness to the Lord. —The words seem to reverse the rule of Deuteronomy 23:18, which, probably not without a reference to practices like those connected with the worship of Mylitta (Herodotus, 1.99), forbade gifts that were so gained from being offered in the Sanctuary. Here, it seems to be implied, the imagery was not to be carried to what might have seemed its logical conclusion.

The harlot city, penitent and converted, might be allowed, strange as it might seem, to bring the gains of her harlotry into the temple of the Lord. Interpreted religiously, the prophet sees the admission of proselytes to the worship of Israel in the future, as he had seen it probably in the days of Hezekiah (Psalms 87:4). Interpreted politically, the words point to a return to the old alliance between Judah and Tyre in the days of David and Solomon (1 Kings 5:1–12), and to the gifts which that alliance involved (Psalms 45:12).

For them that dwell before the Lord ... —These were probably, in the prophet’s thoughts, the citizens of Jerusalem, who were to find in Tyre their chief resource both for food and clothing. Traces of this commerce after the return of the Jews from captivity are found in Nehemiah 13:16, men of Tyre bringing fish and all manner of ware to the gates of Jerusalem. Of the more direct service we find evidence in the fact that Tyrians and Sidonians contributed to the building of the second Temple, as they had done to that of the first (Ezra 3:7).