With the mention of Zoar is this clause subjoined in Isaiah, Eglath Shelishijah, or "a heifer of three years old." So with the mention of Zoar and Horonaim, the same clause is also subjoined in Jeremiah.
Isaiah 15:5: "His fugitives unto Zoar, a heifer of three years old."
Greek; "In it unto Sego. For it is a heifer of three years."
Vulgar: "Its bars were unto Segor: a heifer in his third year."
Targum: "That they should fly as far as Zoar, a great heifer of three years old."
English: "His fugitive shall flee unto Zoar: a heifer of three years old."
Jeremiah 48:34: "From Zoar to Horonaim, a heifer of three years old."
Vulgar: "From Segor unto Horonaim, the heifer being in her third year." And so others.
I am not ignorant what commentators say upon these places: but why may not Eglath Shelishijah be the name of some place, and so called a third Eglah, in respect of two other places much of the same sound...
There is mention of Ein Eglaim, in that country, Ezekiel 47:10; where Eglaim is plainly of the dual number, and seems to intimate that there were two Egels, with relation to which this our Eglah may be called Eglah the third. So Ramathaim, 1 Samuel 1:2, is of the dual number, and plainly shews there were two Ramahs.
The sound of the word Necla comes pretty near it. This we meet with in Ptolemy, in Arabia Petraea: Zoar 18.104.22.168.; Thoan 22.214.171.124.; Necla 126.96.36.199.
So that here we see the geographer mentions Zoar and Necla, as the prophet before had Zoar and Eglah: and how easily might Eglah pass into Necla in Greek writings, especially if the letter Tzadai hath any thing of the sound of the letter n in it. The geographer makes the distance of Zoar from Necla to be fifteen miles: so, we may suppose, was the distance of Zoar from Eglah, Horonaim lying between them; from whence the words of the prophet may not be unfitly rendered thus:
"His fugitives shall flee unto Zoar, unto the third Eglah.
From Zoar unto Horonaim: even unto the third Eglah."
I am deceived if Agalla, which we meet with in Josephus, be not the Eglah we are now speaking of: numbering up the twelve cities, which Hyrcanus promised he would restore to Aretas, the Arabian king, being what his father Alexander had taken from him: amongst the rest he nameth Agalla, Athone, Zoar, Horonae. Of Zoar there can be no scruple; and as little of Horonae; but, by that must be meant Horonaim. Athone, seems to bear a like sound with Ptolemy's Thoana; and Agalla, with his 'Necla,' and that with our 'Eglah.'