WORD OF GOD (Numbers 3)

A very familiar phrase crept into today's reading: Moses turned over the redemption money to Aaron and his sons, as he was commanded by the word of God. (Numbers 3:51, MSG)

I did a quick search, and the only earlier reference to the "word of God" comes in Genesis 15, where the word of God said, "Don't be afraid, Abram. I am your shield. Your reward will be grand!"

In addition to the fact that God inspired the Bible, the word of God, God dictated much of the Pentateuch word-for-word. In some ways, I'm surprised that I haven't run across the phrase "the word of God" before now. I ask myself, why here? why in connection with this command? what does it mean? 

The redemption money referred to is the tax the people of Israel had to pay, to make up the difference between the total number of first-born males and the total number of Levites. The Levites as a tribe took the place of the first-borns, but there was a slight imbalance.

In the New Testament, believers are redeemed, bought with the blood of Jesus Christ--the other Word of God.

So does the word of God in Numbers refer to another command and nothing more?
Does it foreshadow the Word which would pay the redemption price?
Did the Word of God Himself speak the command to Moses?

Or all three?