Jamieson, Fausset and Brown on Numbers 33:2

2. Moses wrote their goings out according to their journeys by the commandment of the Lord--The wisdom of this divine order is seen in the importance of the end to which it was subservient--namely, partly to establish the truth of the history, partly to preserve a memorial of God's marvellous interpositions on behalf of Israel, and partly to confirm their faith in the prospect of the difficult enterprise on which they were entering, the invasion of Canaan.