Albert Barnes Commentary Joshua 22:7-8

"Now to the one half-tribe of Manasseh Moses had given [inheritance] in Bashan; but unto the other half gave Joshua among their brethren beyond the Jordan westward; moreover when Joshua sent them away unto their tents, he blessed them, and spake unto them, saying, Return with much wealth unto your tents, and with very much cattle, with silver, and with gold, and with brass, and with iron, and with very much raiment: divide the spoil of your enemies with your brethren." — Joshua 22:7-8 (ASV)

The insertion of this explanation about the half tribe, and the repetition of Joshua’s farewell, are examples of a marked characteristic of very ancient writers, and of Hebrew writers as much as any: that of giving a completeness and finish to each section of their story. The Jewish historian scarcely ever quotes or reminds, but instead repeats as much as may be necessary to make his account of the current transaction fully understandable on its own (Joshua 13:33; Joshua 14:3; Joshua 18:7).

It is quite possible, however, that the specific details in Joshua 22:8 may be due to some other narrative of the whole event than that to which Joshua 22:5 belongs, and may have been interwoven by a later reviser.