God specifically chose to reveal his Law to the man Moses.  Moses in turn revealed it to God’s people Israel.  Prior to this, however, God chose a man to act as Moses’ prophet, his brother Aaron.

And Moses said before the LORD, Behold, I am of uncircumcised lips, and how shall Pharaoh hearken unto me? And the LORD said unto Moses, See, I have made thee a god to Pharaoh: and Aaron thy brother shall be thy prophet. Thou shalt speak all that I command thee: and Aaron thy brother shall speak unto Pharaoh, that he send the children of Israel out of his land. (Exodus 6:30-7:2 KJV)

Exodus 7:1 constitutes only the second time in Scripture where God uses the word “prophet.”  The first use of this word occurs in Genesis 20:7 when God revealed to Abimelech that Abraham was God’s prophet.  The word prophet simply means “an inspired man,” or one who “speaks forth the words of God.”  Henceforth, after God chose Moses as lawgiver and appointed  Aaron his prophet, these two acted in concert as God’s witness to the greatest king on earth, Pharoah, king of Egypt.

These two men, then, representing the Law and the Prophet, set forth a pattern that we see repeated often in Scripture.  Following are a few verses which make this clear:

Yet the LORD testified against Israel, and against Judah, by all the prophets, and by all the seers, saying, Turn ye from your evil ways, and keep my commandments and my statutes, according to all the law which I commanded your fathers, and which I sent to you by my servants the prophets.  (2 Kings 17:13 KJV)

The priests said not, Where is the LORD? and they that handle the law knew me not: the pastors also transgressed against me, and the prophets prophesied by Baal, and walked after things that do not profit. (Jeremiah 2:8 KJV)

Her prophets are light and treacherous persons: her priests have polluted the sanctuary, they have done violence to the law. (Zephaniah 3:4 KJV)

Yea, they made their hearts as an adamant stone, lest they should hear the law, and the words which the LORD of hosts hath sent in his spirit by the former prophets: therefore came a great wrath from the LORD of hosts.  (Zechariah 7:12 KJV)

Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil. (Matthew 5:17 KJV)

Therefore all things whatsoever ye would that men should do to you, do ye even so to them: for this is the law and the prophets. (Matthew 7:12 KJV)

And when they had appointed him a day, there came many to him into his lodging; to whom he expounded and testified the kingdom of God, persuading them concerning Jesus, both out of the law of Moses, and out of the prophets, from morning till evening. (Acts 28:23 KJV)

Thus we see that through Moses God established his first witness, the Law, and through Aaron, his second, the prophet.  From this time on these two witnesses testified to the truth concerning God and his Christ, Jesus the Anointed One, the Messiah.  The Law and the Prophets still so testify today.