Numbers 34:3

והיה לכם פאת נגב THE SOUTHERN פאה SHALL BE UNTO YOU — i.e. the south side which extends from east to west (פאה does not here mean “corner”). ממדבר צין FROM THE WILDERNESS OF ZIN which is next to Edom there begins the south-east comer of the land of the nine tribes. How is this so? Three lands are situated to the south of the Land of Israel, one next to the other; part of the land of Egypt, and the whole land of Edom, and the whole of the land of Moab. The land of Egypt is at the south-west comer, as it is said in this section, (v. 5) that the southern boundary shall pass “from Azmon unto the Brook of Egypt, and the goings out thereof shall be at the sea” (i.e., at the west). Now the Brook of Egypt ran along the whole land of Egypt — as it is said, (Joshua 13:3) “From the Shihor which is before Egypt”, and divided the land of Egypt from the land of Israel. The land of Edom is next to it on its east. The land of Moab is next to the land of Edom at the end of the south side of Palestine at the east (i.e., the south eastern corner). — When Israel came out of Egypt if the Omnipresent had wished to bring about their entry into the Land quickly, he would have led them over the Nile northwards and they would have so come into the Land of Israel; but He did not do so. This is what is stated, (Exodus 13:17) “And God did not lead them by way of the land of the Philistines” who dwelt by the sea in the west of the land of Canaan — just as it is said of the Philistines, (Zephaniah 2:5) “inhabitants of the sea-coast, the nation of the Cherethites”. — However, He did not lead them by that route, but He made them travel round, and brought them out by a southern route into the wilderness. It is that which Ezekiel (Ezekiel 20:35) calls “the wilderness of the peoples”, because several peoples dwelt beside it. Then they proceeded along the south always from the west to the east, until they came to the south of the land of Edom. They asked of the king of Edom that he should permit them to pass by way of his land and to enter the land of Palestine along its (Edom’s) breadth. He, however, refused, and they were compelled to travel along the whole south of Edom until they came to the south of the land of Moab, as it is said, (Judges 11:17) “And also to the king of Moab he sent, but he refused”. Therefore they proceeded along the whole south of Moab unto its very end, and from there they turned their faces to the north until they had gone along its entire eastern boundary along its breadth. Wien they arrived to the end of its eastern side, they came upon the land of Sihon and Og who dwelt at the east of the land of Canaan with the Jordan dividing them (dividing the land of Sihon and Og from Canaan). This is what is stated in the history of Jephthah, (Judges 11:18) “Then he (Israel) went through the wilderness and compassed the land of Edom and the land of Moab and came by the east of the land of Moab”. They subdued the land of Sihon and Og which was on the north of Moab and they approached right up to the Jordan, which was opposite the north-west corner of the land of Moab. It follows therefore that the part of the land of Canaan which was on the west side of the Jordan had its south-east corner next to Edom. (This explains the words והיה לכם פאת נגב … על ידי אדום in our text.)

וְהָיָ֨ה לָכֶ֧ם פְּאַת־נֶ֛גֶב מִמִּדְבַּר־צִ֖ן עַל־יְדֵ֣י אֱד֑וֹם וְהָיָ֤ה לָכֶם֙ גְּב֣וּל נֶ֔גֶב מִקְצֵ֥ה יָם־הַמֶּ֖לַח קֵֽדְמָה׃

then the Negev quarter shall be from the wilderness of Żin along by the border of Edom, and your south border shall be the outmost coast of the Salt Sea eastward: