Commentaire sur Le Deutéronome 3:3

ויתן ה׳ אלוקינו בידנו, G'd delivered into our hands, etc. This verse is best explained by reference to Berachot 54 describing Og as uprooting a mountain of 12 kilometers (equal to the size of the encampment of the Jewish people) and trying to throw it onto the camp of the Israelites. G'd frustrated this plan. Thereupon Moses, who was ten cubits tall, took an axe ten cubits long and threw it at Og, hitting his ankles and killing him. The words ויתן ה׳ refer to G'd making the mountain Og had uprooted drop on his own neck, whereas the word בידנו refers to Moses personally having killed Og using his own hands. Although Moses used only a single hand, the Torah describes his acts by referring to "hands," using the plural ending, much as G'd has been described in Genesis 1,26 as in the plural when He was about to create Adam and said: "let us make a human being, etc." Moses' hand was considered as equivalent to the combined hands of all the Jewish people.