Or HaChaim on Deuteronomy 31:3/אור החיים על דברים ל״א:ג׳

1 ה אלוקיך הוא עובר לפניך…הוא ישמיד "The Lord your G'd will personally cross ahead of you;…He will destroy these nations, etc." Moses had to repeat the word הוא, "He," a second time as he intended to console the people over his own death which represented a double loss for them. Firstly, it had been he who had repeatedly protected the people from G'd's anger such as at the episode of the golden calf and then again when G'd had threatened to wipe out the people after they had accepted the majority report of the spies. Secondly, Moses had defeated the two mighty kings Sichon and Og. They would therefore be concerned who would take Moses' place should the need arise.

2Concerning the fact that he had been able to assuage G'd's anger on two critical occasions, he now said that G'd would עובר לפניך, in the sense this word occurred in Exodus 17,5 where G'd had said to Moses עבור לפני העם, suggesting that Moses forgive, "pass over" the sins he had accused the people of committing. At that time, G'd wanted the miracle of producing water to be credited to Moses rather than to Himself. On another occasion, immediately after the sin of the golden calf, G'd had said to Moses: "Let Me be so that I can destroy the people." In other words, it had been G'd who had given Moses a hint that his prayer might help (Exodus 32,9). In view of this Moses said: "He will pass over your sins Himself;" you do not depend on me doing this for you.

3As far as Moses' prowess in warfare, He told the people that it was not his own personal strength which had performed all these valiant deeds but that G'd had been the real Warrior. As to the means G'd would employ in His fight against the Canaanites, Moses cited Joshua as the official representative who would march at the head of the army.

4He emphasised the word הוא, "he," to make clear that the fact that Joshua marches at the head was crucial. When the army of Israel [a small contingent of about 3.000 men. Ed.] suffered a defeat at the town of Ai (Joshua 7,5-15) and there were about 36 Jewish casualties, Joshua is reported as falling on his face complaining to G'd. One of the reasons cited by the Talmud Sanhedrin 44 for this defeat was that Joshua had not been at the head of that army contingent. He had not considered the objective as deserving his personal attention. Moses here stresses that it is Joshua's task to walk in front of the army.