Rashi

On that day there shall be five cities, etc. We learned in Seder Olam (ch. 23): Following Sennacherib’s defeat, Hezekiah stood up and released the armies he had brought with him from Egypt and from Cush in chains before Jerusalem, and they imposed upon themselves the kingdom of heaven, and returned to their place, and it is said: “On that day there shall be five cities, etc.” They went and built an altar to the Lord in the land of Egypt and they would sacrifice on it to heaven, to fulfill what was said: On that day there shall be an altar to the Lord in the land of Egypt. Some of our Sages expounded it in the tractate Menahoth (109b) as referring to the altar of the temple of Onias the son of Simon the Just, who fled to Egypt and built an altar there. speaking the language of Canaan like the Israelites in the land of Canaan. one of which will be called “the city of Heres.” Jonathan paraphrases: The city of Beth-shemesh which is destined to be destroyed will be said to be one of them. Jonathan renders “Heres” in two ways: an expression related to (Job 9:7) “Who says to the sun (לַחֶרֶס) and it will not shine,” [הֶרֶס and חֶרֶס being interchangeable since ‘heh’ and ‘heth’ are both gutterals,] and an expression of demolition and destruction. (Some editions add:) And whence did Jonathan derive this? From Jeremiah’s prophecy, which he prophesied in Tahpanhes (43:13): “He shall also break the monuments of Beth shemesh which is in the land of Egypt.” We learn from here that Beth-shemesh that was in the land of Egypt [and the monument] was destined to be destroyed, and the monuments mentioned there are identical with “the monument beside its border, to the Lord,” mentioned here, and it may be said that Beth-shemesh was situated in the border of Egypt on the boundary. Therefore it is stated: Beside its border.