This is what Moses had given to the clans of the tribe of Reuben:
15. And Moses gave unto the tribe, etc What he seemed to have said with sufficient clearness he now follows more fully in detail, not only that the reading might incite the people to gratitude, seeing the divine goodness recorded in public documents, and, as it were, constantly before their eyes, but also that each might enjoy his inheritance without molestation and quarrel.
Here we have, I. Orders given to Joshua to assign to each tribe its portion of this land, including that which was yet unsubdued, which must be brought into the lot, in a believing confidence that it should be conquered when Israel was multiplied so as to have occasion for it (Jos 13:7): Now divide this land. Joshua thought all must be conquered before any must be divided.
Commenting on Joshua 13:7-33
And Moses gave unto the tribe of the children of Reuben inheritance according to their families. According to the number of them, and sufficient for them. And Moses gave unto the tribe of the children of Reuben inheritance according to their families. According to the number of them, and sufficient for them.