From the fact that Hashem told Moshe not to fear Og, the Torah was suggesting that Moshe had reason to fear him. What could there be about Og that would engender fear in Moshe. As Rashi says, Og had received merit for a good deed that he had performed many years earlier. Og was the one who told Avraham that Lot had been taken captive. This act of kindness gave him a zechus. The question is obvious. Og had an ulterior motive in communicating this message to Avraham. Chazal tell us that Og hoped Avraham would rush into battle…
