John Calvin Commentary Deuteronomy 2:13

"Now rise up, and get you over the brook Zered. And we went over the brook Zered." — Deuteronomy 2:13 (ASV)

Now rise up. He now proceeds with what he had begun in verse 9, namely, that God had commanded them to pass by the land of Seir and to advance to the brook Zered; meaning that after they had been subdued by their misfortunes, they were prohibited from further progress until God opened the way before them, and so they were to follow Him as their leader, and not make a passage for themselves at their own discretion.

He afterwards specifies the period of delay they had been compelled by God to endure in the desert, after they had once reached the borders of the promised land. He says, then, that after thirty-eight years they had at last returned to the land from where they had been obliged to retire; and briefly reminds them how long the course of their deliverance had been interrupted through their own fault, from the time they had set out to enjoy the promised land. He calls those “warlike men,” or, in Hebrew, “men of war,” whose age entitled them to bear arms, that is, who had exceeded their twentieth year.

When forty years are mentioned elsewhere, the two years spent both in Mount Sinai and in other places are then included; and with good reason, because during that time also, their sins prevented them from passing to the enjoyment of their inheritance immediately after the promulgation of the law.