What was Moses's sin?

This week Moshe commits some unforgivable sin, and is banned from entering the promised land. But what did he do wrong? The nature of Moshe's sin is the source of much controversy among the big names.

- Rashi, recycling an aggada first found in Sifrei, says Moshe's mistake was hitting the rock instead of speaking to it.

- Ramban gives Rashi what comes across as a condescending pat on the head (There, there. What a nice aggada.) before asking: "If he wasn't supposed to hit the rock, why did God tell him to take the staff?" In the view of the Ramban Moshe sinned when he said "can we get water from this rock?" This made it seem like the miracle would be done through his own powers, and not by the hand of God. (Hasidic Rabbis who perform mofsim are hereby put on notice)

- Rambam in Shemonah Perakim says Moshe sinned by getting angry, and thereby suggesting to the people that God was angry when He was not. The Ramban thinks this suggestion is "vanities on top of vanities" i.e. a lousy answer in the extreme.

- Ibn Ezra goes a little Kabbalistic, and says some things about Moshe and his prayerful concentration before concluding the the sin was hitting the rock twice instead of once. Ramban's reaction to this answer brings to mind Nelson Muntz (Hah-Ha!)

- Abravanel is a bit more polite then the Ramban as he goes through the pros and cons of ten possible sins, all expertly weighed and considered by Josh Waxman here. (scroll down)

- Shadal, reacting to all of this, has the best line. He says: "Moshe Rabbenu only sinned one sin, but the commentators burdened upon him 13 sins and more, for each one invented of his own heart a new sin." (saw it on Josh's blog)

No disrespect to the medieval commentators (who, as you know, I adore) but they're late to the party. Often, the earliest commentators can tell us more about how the verses were first understood. One such early commentator, usually left unconsidered when the various interpretations of Moshe's sin are reviewed, is the opinion of King David. He, also, was a bible commentator, and his commentary can be found in the Book of Psalms when Biblical events are described. Tehillim 106 mentions Moshe's sin, and describes it his way (KJV): They angered him also at the waters of strife, so that it went ill with Moses for their sakes; Because they provoked his spirit, so that he spake unadvisedly with his lips.

How do you read this? Josh says it means the Psalmist thought Moshe sinned by become angry.

So score one for Rambam?