It certainly wasn't Moses,Jesus said"them of old time" not any "one person".
The discussion about Matt. 5 is who was the "Them" Jesus was speaking about. Moses and the Prophets or the Jews that had corrupted His Word for centuries.
Here is an over view.
Matt.5:
17 Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil.
18 For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled.
It seems Jesus is settled that the Law and Prophets, as written, shall stand. No indication here that there is anything missing, or wrong with the Law and Prophets.
19 Whosoever therefore shall break one of these least commandments,
and shall teach men so, he shall be called the least in the kingdom of heaven:
but whosoever shall do and teach them, the same shall be called great in the kingdom of heaven.
Again, Moses has already given the instructions from God. No indication that there is a problem accept if "MEN" teach folks to break it. Did Moses teach folks to break God's Laws? Did the Jews/Pharisees teach folks to break God's Laws? Jesus said they did and killed the Prophets of old time when He sent them to correct them.
20
For I say unto you, That except your righteousness shall exceed
the righteousness of the scribes and Pharisees, ye shall in no case enter into the kingdom of heaven.
Again, these are the teachers of the Word that had corrupted the Word, and taught others to do the same. You know the scriptures.
21 Ye have heard that it was said by/to them of old time, Thou shalt not kill; and whosoever shall kill shall be in danger of the judgment:
So now, "many" who come in Christ's Name, would have me believe that Jesus just ignored everything He just said about those who are teaching about God's Word. The Scribes and Pharisees that He just rebuked. I am to believe that Jesus changed the subject completely, and is now setting about to change the Laws He just said not one jot or title would pass.
22 But I say unto you, That
whosoever is angry with his brother without a cause shall be in danger of the judgment: and whosoever shall say to his brother, Raca, shall be in danger of the council: but whosoever shall say, Thou fool, shall be in danger of hell fire.
These "many", who come in Christ's Name, would have me believe that the Law and Prophets that He just stood by, is now being changed out of the blue. And that He isn't talking about "MEN" who had corrupted His Fathers commandments for centuries anymore, but instead contradicting Himself and now is saying you can't trust what is written by Moses, and He is changing the instruction to mean something God never told Moses.
But God did tell Moses. Lev. 19:
17 Thou shalt not hate thy brother in thine heart: thou shalt in any wise rebuke thy neighbour, and not suffer sin upon him.
Moses taught this, but the "THEM" of old time did not. either those teaching the "Them of old time" , or the teaching of the "Them of old time", there is no difference, both translations are the same. They said one thing, and Jesus pointed out that He, before becoming a man, said something different as it is written.
So the truth is Jesus is speaking about the Jews who had corrupted God's Commandments by teaching parts of His Word, but omitting the "Weightier matters of the Law" like mercy, Faith, Judgment. He touched on this again in Matt. 23.
23 Woe unto you, scribes and Pharisees, hypocrites! for ye pay tithe of mint and anise and cummin, and have omitted the weightier
matters of the law, judgment, mercy, and faith: these ought ye to have done, and not to leave the other undone.
The preaching that Jesus was speaking about Moses and the Prophets and not the Scribes and Pharisees who had corrupted God's Word in Matt. 5 is a lie, a deception.
People use this lie to justify rejecting God's Instructions, mostly the Sabbath.
"Jesus changed adultery and murder, could He also change the Sabbath?
He didn't change the meaning of any of God's Instructions in Matt. 5.. The Law and the Prophets taught the very same things Jesus taught, but the Scribes and Pharisees did not.
He was correcting their teaching of the Jews that had deceived so many people for centuries, not God or Moses or the Prophets as some on this forum preach.