וּגְב֣וּל יָ֔ם וְהָיָ֥ה לָכֶ֛ם הַיָּ֥ם הַגָּד֖וֹל וּגְב֑וּל זֶֽה־יִהְיֶ֥ה לָכֶ֖ם גְּב֥וּל יָֽם׃
서편 경계는 대해가 경계가 되나니 이는 너희의 서편 경계니라
Rashi
You will look from the peak of Amanah. When I gather your dispersed ones, you will look and ponder what is the reward of your actions from the beginning of your faith [=מֵרֹאשׁ אֲמָנָה that you believed in Me, [e.g.,] your following Me in the wilderness,54See Yirmiyahu 2:22. and your travels and your encampments at My command,55See Bamidbar 9:17-23. and your coming to the peak of Snir and Chermon, which were the lions’ dens, Sichon and Og. Another explanation, “מֵרֹאשׁ אֲמָנָה” [=from the peak of Amanah], this is a mountain on the northern boundary of Eretz Yisroel, named Amanah. In the language of the Mishnah,56Maseches Gittin 8a. [these are] the mountains of Amnon [or] Mount Hor, about which it is stated, “from the Great Sea you shall draw a line extending to Mount Hor.”57Bamidbar 34:7. When the exiles gather and arrive there, they will look from there and see the boundary of Eretz Yisroel and the air of Eretz Yisroel, and they will rejoice and offer thanks. Therefore, it is stated, “תָּשׁוּרִי [=You will sing] from the peak of Amanah.”