Moses would have this done, partly to evince the truth of the history, partly to preserve the remembrance of God's glorious and miraculous works both of judgment and mercy towards his people, and thereby to confirm their faith in their present difficult undertaking.
Related Commentaries of Numbers 33:2
Numbers 33:2
2 And Moses wrote their goings out according to their journeys by the commandment of the LORD: and these are their journeys according to their goings out.