Parshas Va'eschanan starts off with Moshe's Prayer to Hashem. Rashi comments that he asked for a free gift. Why was he asking for a free gift?
Rashi indicates that a Tzadik does not make requests based on their merits. Perhaps the explanation of Rashi is that a Tzadik truly recognizes that any merit he might have before God is really as nothing. If one truly perceives the reality of God and recognizes how lowly man is, as is said " Mah enosh Ki ziskerenu?" What is man but nothing before God, he knows that he can make no demands or truly merit anything. It is with this perception that a Tzadik does not make requests based on his merits, but asks based on Matnas Chinam, a gift from God. Meaning a he recognizes he truly does not deserve it, but asks God to assist him in his pursuit of development.
The Imrie Shefer Answers that if you remember by Avraham after he conquered the 5 kings he was afraid he had used up all his credit for his righteousness so Hashem told him
אל תירא אברם שכרך הרבה מאד
Here too Moshe had the same concern,he had just conquered Sichon and Og so he asked for a free gift. Therefore Hashem answered him
רב לך,You have got plenty of credit it is nothing to worry about.
The Zohar says we come into this world to accomplish, in order not to get MiNahman Dikusufah-Bread of Shame, in that we revived a gift without working for it so how does it add up? The Talile Oros of Rav Klar brings that the only time it is a shame to ask is if you are poor meaning in our example you lack Mitzvos but if you are rich than asking is no problem, as they know you have the money to pay, and they even might want to give you a gift to keep you coming back Hence the Problem of getting gifts MiNahman Dikusufah-Bread of Shame for tzaddikim and especially Moshe is a non issue.