Albert Barnes Commentary Job 42:15

"And in all the land were no women found so fair as the daughters of Job: and their father gave them inheritance among their brethren." — Job 42:15 (ASV)

And their father gave them inheritance among their brethren - This is mentioned as a proof of his special regard, and is also recorded because it was not common.

Among the Hebrews the daughter inherited only in the case where there was no son (Numbers 27:8). The property was divided equally among the sons, with the exception that the oldest received a double portion; see Jahn’s “Bib. Arch.” section 168.

This custom, still prevailing extensively in the East, it seems, existed in the time of Job, and it is mentioned as a remarkable circumstance that he made his daughters heirs to his property with their brothers. It would also be rather implied in the passage before us that they were equal heirs.