Sedar Chukas, 120 words. Reasons not to Trust Gd
And Gd said to Moshe, “Don’t be scared of him (Og, the invincible warrior)” [Bamidabar 21:34]
In fact, Moshe WAS scared. [Rashi]
Moshe was scared [he failed to trust] in spite of Gd’s instruction to wage war, which one must assume carries an inherent guarantee of success.
But Moshe Rabbenu was not scared of Og’s muscles, cunning, strategies or weapons.
Moshe was scared that Og had a merit. Og contributed to saving a life. He had performed a Mitzvah. Og had advised others that a righteous man was in trouble.
Did Og, the great warrior, actually fight to save this man? No.
What did Og do? He brought information to the family of the kidnapped man.
Was Og an altruist? Our Sages suggest that he had an ulterior selfish motive.
In spite of all this Moshe was scared. The Torah records for posterity that Gd had to reassure Moshe Rabbenu not to fear this merit of Og.
We [obviously] do not understand the power of a good deed. [I am reluctant to describe it as a Mitzvah not only because of Og’s false motives but because I don’t think Og believed in Gd]