Jamieson-Fausset-Brown on Ezekiel 48:6
Reuben--doomed formerly for incest and instability "not to excel" (Gen 49:4). So no distinguished prophet, priest, or king had come from it. Of it were the notorious Dathan and Abiram, the mutineers. A pastoral and Bedouin character marked it and Gad (Jdg 5:16).
Adam Clarke on Ezekiel 48:1
Now these are the names of the tribes - See the division mentioned Num 34:7-12, which casts much light upon this.
John Gill on Ezekiel 48:6
And by the border of Ephraim, from the east side unto the west side, a portion for Reuben. Who, through his sin, lost his birthright; but now, his sin being forgiven and forgotten, has a portion assigned him upon the border of Ephraim, and next to the tribe of Judah; when in Moses and Joshua's time it lay on the other side Jordan: this points to such persons that shall have their lot and portion in spiritual things; that "see the Son", that look to Christ alone for righteousness, peace, pardon, and eternal life.
Tyndale Open Study Notes on Ezekiel 48:1-8
The land assigned to the tribes was arranged in strips running east to west through the land, rather than piecemeal as it was before the Exile. This was more than simply a way of ensuring that each tribe received equal access to the various resources of the land. It aligned the land with the sacred east–west axis that was so prominent in the Temple. As in the Temple, the size and shape of the central areas were clearly defined, while those on the margins were less closely determined (see study note on 40:17-19). The four tribes most distant from the central sacred section (Dan, Asher, Naphtali, and Gad), and therefore in the least privileged position, were descended from the four sons of Jac…
Read the whole note in the consoleRashi on Ezekiel 48:2
And alongside the border of Dan and alongside the border of Dan to its south.